# My Tread Depth Log at Max Sidewall Pressure



## XtremeRevolution (Jan 19, 2012)

I told everyone I'd do this, so here it goes. 

My Cruze Eco currently has 4,000 miles on it. As promised, I'll be measuring the tread depth as some claimed that I would wear out the inner edges of the tires. 

Tires were rotated at 3,500 and will be rotated every 3,500 moving forward. I have a large compressor and an impact wrench to make the job very quick. Tires will be rotated front to back and will not be crossed. Tire pressure was increased to 50psi at 2,500 miles, which means I've gone 1,500 miles on them with that pressure. 

The measurement will be on 4 locations on the tire. There are 5 total ridges on the tire, but the center cannot be measured as the slits are not wide or deep enough.

The results for today's measurement?

13/64". For all tires, at all locations on the tire. 










Next measurement will be posted at 7,000 miles.

Side note: these are definitely not the real Goodyear Assurance FuelMax tires (as someone truthfully pointed out). The real ones have a tread depth of 10/32" (or 20/64") when new and I can guarantee you that I didn't chew through 7/64" of tire in 4,000 miles while averaging 38.9mpg. These are simply cheap OEM spec tires designed to last you likely half of what a new tire would.


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## obermd (Mar 3, 2012)

You should rotate cross pattern as well. Front tires go straight back and the rear tires cross over as they go forward. This is the recommended pattern in the owner's manual for most cars as well as ensures that any alignment problems generate the same wear on all four tires.

Thanks for doing this. How's the ride at 50 PSI. I think if I go any higher than 40 PSI my wife will refuse to ride in the car.


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## ChuzCruze (Feb 9, 2012)

XtremeRevolution you are a man of your word  Glad to see you are putting this in the forum as you stated you would. I am curious to see how this goes. I will be tracking your progress with great interest.


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## XtremeRevolution (Jan 19, 2012)

obermd said:


> You should rotate cross pattern as well. Front tires go straight back and the rear tires cross over as they go forward. This is the recommended pattern in the owner's manual for most cars as well as ensures that any alignment problems generate the same wear on all four tires.
> 
> Thanks for doing this. How's the ride at 50 PSI. I think if I go any higher than 40 PSI my wife will refuse to ride in the car.


I called up my buddy Bob who works at a Firestone in Ohio and asked him about this, and he said that with radial tires, they only rotate front to back. If a tire is wearing unevenly due to an alignment issue, then the alignment issue should be fixed. Wearing another tire unevenly won't be the solution. The reasoning for this is that the belts supposedly will shift ever so slightly based on the rotation of the tire and can cause problems. 



> Toyota does not recommend cross rotation of tires. The steel belts are accustomed to being driven in one direction and if cross rotated, belt separation may occur.


I've been reading many variations of the above statement everywhere.

The ride is noticeably firmer than at 35psi. I don't recommend it for someone looking for comfort as you will feel more of the road. It's not technically stiff, as the suspension still has the same spring rate and shocks, but you will feel more of the bumps on the road. I'm doing it to see how much life I can get out of these OEM tires compared to everyone else who will run them at placard pressure and to maximize fuel economy.


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## SlvrECObullet (Feb 21, 2012)

X this is awesome I was just start looking up how to rotate our tires.	I run 48 psi cold in my car and will be rotating my tires at 5k when I do my first oil change then 7500 everytime after that. I may do it 2x every oil change so every 5k. Not sure tho. May do tires and oil ever 7500 just make it easy. Great job X. I like following your threads and post!

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## Beaker (Mar 21, 2012)

I'll be doing oil and tire rotations every 5k miles. My tires are currently at 38-40 psi (was this way the day I picked the car up) cold but I think I might bump it up to 45 psi cold. I'm used to a car that can feel the bumps in the road.

I don't know why GM is recommending 7500 mile tire rotations.


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## XtremeRevolution (Jan 19, 2012)

Beaker said:


> I'll be doing oil and tire rotations every 5k miles. My tires are currently at 38-40 psi (was this way the day I picked the car up) cold but I think I might bump it up to 45 psi cold. I'm used to a car that can feel the bumps in the road.
> 
> I don't know why GM is recommending 7500 mile tire rotations.


7500 is probably ok. I'm only doing it every 3500 because I have the tools to do so very easily and it allows me to ensure very even wear on these tires to accurately prove to myself and everyone else whether or not running tires at maximum sidewall pressure causes tires to wear unevenly.


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## obermd (Mar 3, 2012)

OK. Page 10-53 of the 2012 Cruze Owner's manual shows Front directly to Rear and the Rear's change sides on their way to the front. I think this is a good question for Stacy to try to get answered for us. I understand what X is saying - I'd like to know why it doesn't match what Chevy is telling us in the Owner's manual.


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## XtremeRevolution (Jan 19, 2012)

obermd said:


> OK. Page 10-53 of the 2012 Cruze Owner's manual shows Front directly to Rear and the Rear's change sides on their way to the front. I think this is a good question for Stacy to try to get answered for us. I understand what X is saying - I'd like to know why it doesn't match what Chevy is telling us in the Owner's manual.
> 
> View attachment 4559


GM is in absolutely no position to be giving us recommendations on tire rotations. They provide us with a tire that has half of it's usable *safe *tread life compared to the retail tire named Goodyear Assurance FuelMax that we can find in a tire store in an effort to ensure that we only get 30k miles out of it if not less, and they don't warranty those tires for mileage or any other tires we put on the car thereafter. 

If GM were to accept liability for damages to tires as a result of their rotation requirements for every tire I put on my car while I own it, I'd rotate them exactly as they recommend, but since they don't, what they say means nothing to me.


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## Beaker (Mar 21, 2012)

Walmart sells cheaper variants of named tires as well. Hence why I don't go there.


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## ChuzCruze (Feb 9, 2012)

When I worked at a GM dealer in the 90's we rotated front to back...never crossed them.


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## GoldenCruze (Dec 18, 2011)

I have to bring up a point about the discussion of inflation pressures. There are different trim levels of Cruze's with different tires. The OP here says that he is using 50psi on the Goodyear tires mounted on his Eco. Another poster in this thread said that his Cruze came off the dealers lot with 38-40 inflation pressures, but i dont know what tire he has. I have the 2LT with Continental ContiProContact tires mounted on it. And the listed max inflation for these tires is 44psi. If I go along worth inflating the tire to 50psi it will be well beyond the design of the tire. So it is important to state exactly what trim level you have and what tire when discussing inflation pressures on your car.


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## ChuzCruze (Feb 9, 2012)

I believe most people have been stating that they are using max listed sidewall tire PSI or less. It is wise to check your tires actual sidewall max PSI before adding additional pressure...but I would think that would be common sense


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## XtremeRevolution (Jan 19, 2012)

GoldenCruze said:


> I have to bring up a point about the discussion of inflation pressures. There are different trim levels of Cruze's with different tires. The OP here says that he is using 50psi on the Goodyear tires mounted on his Eco. Another poster in this thread said that his Cruze came off the dealers lot with 38-40 inflation pressures, but i dont know what tire he has. I have the 2LT with Continental ContiProContact tires mounted on it. And the listed max inflation for these tires is 44psi. If I go along worth inflating the tire to 50psi it will be well beyond the design of the tire. So it is important to state exactly what trim level you have and what tire when discussing inflation pressures on your car.


This thread was created in response to this 12 page thread:

http://www.cruzetalk.com/forum/27-fuel-economy/5733-tire-psi-max-mpgs.html



ChuzCruze said:


> I believe most people have been stating that they are using max listed sidewall tire PSI or less. It is wise to check your tires actual sidewall max PSI before adding additional pressure...but I would think that would be common sense


Correct. The Cruze Eco's tires are rated for a max sidewall of 51psi. It _should _be common sense that one shouldn't inflate their tires beyond their max sidewall rating.


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## silverram323 (Mar 16, 2012)

Mine are at 44psi, also max psi rated for firestone fr170 tires

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## SlvrECObullet (Feb 21, 2012)

I have an ECO hence the name at 48. We should prolly spell it out for people tho cause me being AD Navy alot of people I come across dont have common sence, so I wouldn't put it past someone to copy the PSI some of us run and not paying attention their side wall max... and the getting mad at us in the event of a freek accident like the engine block crack stated in another post.

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## XtremeRevolution (Jan 19, 2012)

SlvrECObullet said:


> I have an ECO hence the name at 48. We should prolly spell it out for people tho cause me being AD Navy alot of people I come across dont have common sence, so I wouldn't put it past someone to copy the PSI some of us run and not paying attention their side wall max... and the getting mad at us in the event of a freek accident like the engine block crack stated in another post.
> 
> Sent from my SCH-I500 using AutoGuide.com App


I don't think that would really be possible. Even 5psi over max sidewall would not be enough to damage the tire. You'd have to double the sidewall rating before you start having to worry about something. Keep in mind that these tires are designed to be filled at their max sidewall pressures when cold. Say you fill them up on a 70 degree morning, and it gets up to 100 degrees that day in hot baking sun and you're driving at 70mph over the pavement. Chances are your tires will heat up enough from what they were earlier to get you more than 5psi what they were earlier. 

That said, I agree with you that some people just don't pay attention. While I know the manufacturers built in a huge margin of safety, I wouldn't recommend anyone exceed the max sidewall pressure cold.


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## obermd (Mar 3, 2012)

I think you misunderstood my post. What I'm trying to do is understand why cross patterns are bad for radial tires. I understand Toyota's issue as I actually have the Toyota service manual on how to eliminate pull in a properly aligned vehicle. (Toyota designs the suspension to drift to the right.) However, what I don't understand is why cars designed to go straight when properly aligned shouldn't have their tires cross rotated. I have always crossed my tires when rotating them and frequently get longer tread life than the rating on the tires.


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## XtremeRevolution (Jan 19, 2012)

obermd said:


> I think you misunderstood my post. What I'm trying to do is understand why cross patterns are bad for radial tires. I understand Toyota's issue as I actually have the Toyota service manual on how to eliminate pull in a properly aligned vehicle. (Toyota designs the suspension to drift to the right.) However, what I don't understand is why cars designed to go straight when properly aligned shouldn't have their tires cross rotated. I have always crossed my tires when rotating them and frequently get longer tread life than the rating on the tires.


Because supposedly, cross rotating changes the direction the tire is turning and as a result, has a possibility to cause the belt(s) to move. So long as there isn't an alignment problem with the car, this shouldn't wear any given tire or pair of tires more than the others.


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## obermd (Mar 3, 2012)

Thank you.


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## SkullCruzeRS (Nov 3, 2011)

In addition a lot of tires are directional tread designed which only allow rotating front to back unless you un-mount the tires and flip them around to go on the other side of the vehicle.


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## XtremeRevolution (Jan 19, 2012)

SkullCruzeRS said:


> In addition a lot of tires are directional tread designed which only allow rotating front to back unless you un-mount the tires and flip them around to go on the other side of the vehicle.


This is true, and should indicate that there's really nothing wrong with doing it this way. I will probably find myself a good set of uni-directional tires to replace the current ones when they wear down or rot.


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## buckeyewalt (Mar 10, 2012)

XtremeRevolution said:


> I called up my buddy Bob who works at a Firestone in Ohio and asked him about this, and he said that with radial tires, they only rotate front to back. If a tire is wearing unevenly due to an alignment issue, then the alignment issue should be fixed. Wearing another tire unevenly won't be the solution. The reasoning for this is that the belts supposedly will shift ever so slightly based on the rotation of the tire and can cause problems.
> 
> 
> 
> ...


Back in the "old days" of bias-ply tires, cross rotating was the norm,,,now with radial tires rotating front to rear-rear to front is recomended (Bridgestone Tires)!


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## GoldenCruze (Dec 18, 2011)

There are several patterns for rotating tires as shown here: Tire Tech Information - Tire Rotation Instructions

I see nothing wrong with using the pattern listed in the owners manual for the Cruze.


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## XtremeRevolution (Jan 19, 2012)

GoldenCruze said:


> There are several patterns for rotating tires as shown here: Tire Tech Information - Tire Rotation Instructions
> 
> I see nothing wrong with using the pattern listed in the owners manual for the Cruze.


That may be so, but again, the manual does not know what kind of tires I will be installing after the OEM tires are gone (which they seem to try to ensure happens sooner rather than later), and given they aren't warrantied by GM, I'll be installing front to back. It makes it easier and quicker for me to rotatte front to back since I can lift the entire side of the car with one jack instead of needing to fiddle with jackstands and lifting various opposing points of the car simultaneously.


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## obermd (Mar 3, 2012)

I avoid unidirectional tires for the simple reason that they can't be cross rotated. My Fiero GT could only be cross rotated since the front tires were slightly smaller than the rear tires. Personally I have only had a problem with one set of tires after a rotation and those tires were on their final rotation before being replaced. They had enough tread to get me through the summer safely but not enough for winter driving. Sometimes I have a pull for a few hundred miles after rotation, but nothing that hasn't worked itself out after a tank or so of gas.


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## XtremeRevolution (Jan 19, 2012)

obermd said:


> I avoid unidirectional tires for the simple reason that they can't be cross rotated. My Fiero GT could only be cross rotated since the front tires were slightly smaller than the rear tires. Personally I have only had a problem with one set of tires after a rotation and those tires were on their final rotation before being replaced. They had enough tread to get me through the summer safely but not enough for winter driving. Sometimes I have a pull for a few hundred miles after rotation, but nothing that hasn't worked itself out after a tank or so of gas.


That kind of thing worries me a bit. Having some kind of pull simply doesn't sound normal. 

I'll probably keep these tires till they wear down to 3/32". I'll buy some winter tires on steelies for this winter and run those to allow me to get more life out of my current tires, and just run the Eco wheels again when the weather improves. If it's anything like this past winter has been though, I may not even need winter tires. I have a set on Grand Prix rims for my 95 Regal and I only had to put them on around the middle of January and really only needed them 2 or 3 times.


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## obermd (Mar 3, 2012)

The pull was on my Montana and I checked with several different tire places and they all told me that on AWD vehicles tires can sometimes develop a pull when going from front to back. This wasn't even a "cross" rotation issue, but a difference in how the GM Versitrak system handles front and rear axles. I corrected by simply running one of the tires at a slightly higher pressure (still under the sidewall max) until I replaced the tires that fall. I probably should have replace the tires at that point as they were already almost down to 2/32 but I wanted to wait until the fall. I like to buy new tires in the Sept/Oct timeframe so I have at least one winter with good tread depth.


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## ChevyCruzeLTZ (Apr 7, 2011)

First I'm going to say I'm gonna wath this thread because IMHO you cannot run 50 psi in a cruze without excessive wear to the center of the tread over time.

Second I'll say that if the tires from the factory are different than the service replacement tire it is because they are TPC spec tires, meaning they have to meet certain requirements the replacement tires do not. Amont these requirements are noise, vibration and performance. The deeper tread on the replacement tire may well make the tire louder and give less responsive steering feel. I do not believe this is some plot by GM to make you buy tires before returning your lease.

Third the factory (GM) and most tire manufacturers recommend rotating front wheel drive tires in a "modified x pattern" where the rear tires are moved straight up to the front and the fronts are crossed going to the back. Cross rotating is a subject of contention in the tire industry however this pattern is recommended by most tire manufacturers for optimum tread wear and longevity.


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## XtremeRevolution (Jan 19, 2012)

ChevyCruzeLTZ said:


> First I'm going to say I'm gonna wath this thread because IMHO you cannot run 50 psi in a cruze without excessive wear to the center of the tread over time.
> 
> Second I'll say that if the tires from the factory are different than the service replacement tire it is because they are TPC spec tires, meaning they have to meet certain requirements the replacement tires do not. Amont these requirements are noise, vibration and performance. The deeper tread on the replacement tire may well make the tire louder and give less responsive steering feel. I do not believe this is some plot by GM to make you buy tires before returning your lease.
> 
> Third the factory (GM) and most tire manufacturers recommend rotating front wheel drive tires in a "modified x pattern" where the rear tires are moved straight up to the front and the fronts are crossed going to the back. Cross rotating is a subject of contention in the tire industry however this pattern is recommended by most tire manufacturers for optimum tread wear and longevity.


If the subject line in this thread didn't give it away, I'll go ahead and lay it out for you: this is my thread to report my tread depth and wear patterns, not to determine whether or not tires will wear unevenly in the center. I and everyone who runs max sidewall on cleanmpg and ecomodder forums already know the answer to this: Radial tires are designed to maintain tread uniformity regardless of pressure between ~20-25psi and max sidewall. Don't make the mistake of thinking that I created this thread on a whim and that I did absolutely no research before committing to a 50PSI tire pressure for the life of these tires. More thought, research, and debate went into the reason why this thread exists than you are aware of, so please consider that before you say that *radial *tires will wear unevenly in the center with a "matter-of-fact"-like tone. 

If you want to continue this discussion and argue a topic that I've argued for 13 pages straight, feel free to contribute to this thread after reading it entirely:

http://www.cruzetalk.com/forum/27-fuel-economy/5733-tire-psi-max-mpgs.html

I went into great detail on the design of radial tires in that thread. Therefore, this thread isn't a wath (wash?). That's all I'll say in *my *thread for now. 

Second, these TPC tires will wear down significantly faster than their retail counterpart. I'm not sure who is going to buy an ECO car specifically for fuel economy to save money and actually want to get only half the life out of their tires. I also don't believe that the difference between 7/32" and 10/32" of tread depth will make a notable difference in road noise and handling characteristics. GM simply went cheap here and it's not the first time. 

Third, count Toyota as one of those companies who doesn't recommend that rotation pattern, as well as various Firestone service locations who have noted problems after rotating FWD tires using the crossing method you just described.


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## GoldenCruze (Dec 18, 2011)

ChevyCruzeLTZ said:


> First I'm going to say I'm gonna wath this thread because IMHO you cannot run 50 psi in a cruze without excessive wear to the center of the tread over time.
> 
> Third the factory (GM) and most tire manufacturers recommend rotating front wheel drive tires in a "modified x pattern" where the rear tires are moved straight up to the front and the fronts are crossed going to the back. Cross rotating is a subject of contention in the tire industry however this pattern is recommended by most tire manufacturers for optimum tread wear and longevity.


I can see an "over inflated" tire wearing evenly across the width of the tread. That's what this experiment here is all about.

As far as the recommended rotation pattern for the Cruze goes, the owners manual list a cross front pattern, not a cross rear.


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## ChevyCruzeLTZ (Apr 7, 2011)

I was merely expressing my intrest in this thread and am certainly open to the possibility of being proven wrong. I never implied that your opinion was not well researched. I am well aware of the rotation pattern in the owners manual, it seems GM has either changed their minds or the diagram is a misprint as they have traditionally recommended moving the rear tires straight up to the front to avoid a radial pull condition that can occur when crossing tires going to the front. My personal opinions are based on two decades in the auto repair business and also not "made on a whim". At any rate I will be very interested to see the updates on this thread.


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## DrVette (Dec 6, 2011)

My 2012 ECO's Tires & Specs

Tread Depth @ 3890 mi w/dealer supplied 38 Front/ 37 Rear PSI
LF & RF Equal @ 0.0252"
LR & RR Equal @ 0.0260"


Goodyear Assurance fuel max technology TPC Spec 1406 MS
DOT 4B3R JANR 3611
E13

I've upped mine to 50# F / 49#R and will check weekly for wear pattern change.

I have a pal who owns a large tire wholesale distributorship in Atlanta.
One memorable quote from him
"The maximum tire pressure is not limited to the sidewall specs but rather to the wheel spec.
For maximum tire life, inflate to max sidewall spec, then observe the casting tips for wear during the first few weeks, increase/decrease to obtain proper wear patterns"

I think the center will start to show increased wear IF these tires are wound like those of the past.

However these LLR tires "may" have tighter wire patterns and higher tension plies than non-LLR which may maintain a "level" tread platform at elevated pressures .. 

Time and patience will tell.


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## XtremeRevolution (Jan 19, 2012)

I'd like to share an observation I made yesterday. I was rotating a family friend's tires on a 2004 Ford Focus. She drives it every day as her commuter vehicle and put new tires on it late last year. Tire pressure was at 30psi cold (at 55 degrees F) on all 4 tires. 

All 4 tires had the exact same uneven wear. The shoulders were scrubbed down and there was a blatantly visible "roundness" to them. I didn't care to actually record this, but I measured the tread depth and she was at least 1/32" lower in tread depth on the shoulders than she was in the center. Keep in mind, this was in accordance to what the manufacturer recommended for her car. 

I promptly inflated them to 38psi and asked her to let me know if the ride was too stiff.


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## cecaa850 (Apr 9, 2012)

XtremeRevolution said:


> I'd like to share an observation I made yesterday. I was rotating a family friend's tires on a 2004 Ford Focus. She drives it every day as her commuter vehicle and put new tires on it late last year. Tire pressure was at 30psi cold (at 55 degrees F) on all 4 tires.
> 
> All 4 tires had the exact same uneven wear. The shoulders were scrubbed down and there was a blatantly visible "roundness" to them. I didn't care to actually record this, but I measured the tread depth and she was at least 1/32" lower in tread depth on the shoulders than she was in the center. Keep in mind, this was in accordance to what the manufacturer recommended for her car.
> 
> I promptly inflated them to 38psi and asked her to let me know if the ride was too stiff.


It almost sounds like she typically runs her tires low on pressure. That would explain shoulder wear on all tires. Many people really aren't dilligent when it comes to checking their tire pressure.


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## XtremeRevolution (Jan 19, 2012)

cecaa850 said:


> It almost sounds like she typically runs her tires low on pressure. That would explain shoulder wear on all tires. Many people really aren't dilligent when it comes to checking their tire pressure.


Tire pressure on a Ford Focus is 32psi and she knew that off the top of her head (surprisingly). I confirmed it. 6% pressure too low causing noticeable shoulder wear? That's significantly less variation than you'd get from the heat created by rolling resistance at higher speeds. These tires were clearly not to be used according to the manufacturer's recommended pressure. I question if the manufacturer recommended pressure applies only to the OEM and OEM replacement tires, or to all tires of that size that you can fit on the car. 

Her tires were at 30 and that's because it was 55 degrees out and it was a particularly cold day. At 72 degrees, they would probably be at 32psi as they need to be. She actually wanted me to teach her how to change her own oil, but after seeing how much of a PITA it is on that car, I told her to just bring it to me every time and I'll do it for free.


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## NBrehm (Jun 27, 2011)

You assume they were never run low and never below 30 PSI, it doesn't take long to wear the shoulders out with low air pressure, especially on the highway. I think it is more likely she drove them on low air at some other time.


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## cecaa850 (Apr 9, 2012)

NBrehm said:


> You assume they were never run low and never below 30 PSI, it doesn't take long to wear the shoulders out with low air pressure, especially on the highway. I think it is more likely she drove them on low air at some other time.


Agreed. I don't know anything else off the top of my head that would round off ALL 4 tires. If you personally had been checking them monthly than I wouldn't know what to think. I'd wager that you checked them when they were coincidentally inflated correctly but they had been driven low in the past.


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## obermd (Mar 3, 2012)

Since we know Ford has a history of recommending tire pressures that are too low (Ford Explorer) I wouldn't be surprised if they recommend underinflation on some of their other vehicles. Rounded edges definitely sound like either long term underinflation or an alignment problem to me. XtremeRevolution, you said that the wear was uneven - I'd get an alignment.


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## XtremeRevolution (Jan 19, 2012)

NBrehm said:


> You assume they were never run low and never below 30 PSI, it doesn't take long to wear the shoulders out with low air pressure, especially on the highway. I think it is more likely she drove them on low air at some other time.


She bought the tires in December. They're not that old. She never actually inflated them herself. It's likely that she drove them at that pressure during the winter, in which case they may have been lower, but I don't see 2-3psi making _that _big of a difference over only 4-5 months of driving. I'll never really know. I guess I'll leave this as an observation. Either way, the shoulder wear was visible. Not severe, but visible to a trained eye and I'm glad I caught it in time. 



obermd said:


> Since we know Ford has a history of recommending tire pressures that are too low (Ford Explorer) I wouldn't be surprised if they recommend underinflation on some of their other vehicles. Rounded edges definitely sound like either long term underinflation or an alignment problem to me. XtremeRevolution, you said that the wear was uneven - I'd get an alignment.


Ford does indeed have a bad history in that regard. 

They were uneven as in, shoulder wear. An alignment problem wouldn't really cause all 4 tires to wear exactly the same on both shoulders, at least not from what I know about alignments. I'll check her tire depth again next time she brings me the car for a rotation and report back.


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## Dieselard (Jan 2, 2012)

XtremeRevolution said:


> She bought the tires in December. They're not that old. She never actually inflated them herself. It's likely that she drove them at that pressure during the winter, in which case they may have been lower, but I don't see 2-3psi making _that _big of a difference over only 4-5 months of driving. I'll never really know. I guess I'll leave this as an observation. Either way, the shoulder wear was visible. Not severe, but visible to a trained eye and I'm glad I caught it in time.
> 
> 
> 
> ...


I work in a tire shop, have have seen this a lot. I have seen it more with the 2011-2012 Chevy impala and Malibu with the inflation pressures at 32PSI front and back. All 4 tires are worn on the inside and outside, on every single car (keep in mind these are fleet vehicles and we service them all every 3000-5000 miles, fleet monitors air pressures between that) 
For the Focus having a air pressure of 32PSI, my opinion it is too low. 
An alignment problem will not wear all 4 shoulders the exact same way, thats not enough air pressure.


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## XtremeRevolution (Jan 19, 2012)

Checked my driver's front tire just for kicks earlier. 5,700 miles on the dash. Still no signs of abnormal wear. Tread depth was identical across all ridges as measured earlier. What's interesting is that the tires also didn't wear down at all. Still at 13/64". Next update will be at 7000, when I'll be checking all 4 tires.


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## Stock 87 (Sep 8, 2011)

Just to add a little to the tread thread. I have an ECO manual with 26,000 miles, I always run my tires at 5 psi over recomended. The Dealer rotates them (I don't know how) every 7000 miles. As of now I cannot tell that there has been any wear to the tires. Also expecting to get at least 80k before they need to be replaced


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## XtremeRevolution (Jan 19, 2012)

Stock 87 said:


> Just to add a little to the tread thread. I have an ECO manual with 26,000 miles, I always run my tires at 5 psi over recomended. The Dealer rotates them (I don't know how) every 7000 miles. As of now I cannot tell that there has been any wear to the tires. Also expecting to get at least 80k before they need to be replaced


Gooooood luck with that 80k mile expectation. I highly doubt you'll achieve that. The tires that came on the car had only 7/32" of tread depth when new. The retail Goodyear Assurance tires (the ones you have on now are TPC spec) have 10/32" of tread depth.


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## XtremeRevolution (Jan 19, 2012)

Rotated tires today at 7012 miles and also measured them. These are the measurements I took before the tire was moved.

Front Driver:
12/64
13/64
13/64
12/64

Front Passenger:
12/64
13/64
13/64
12/64

Rear Driver
13/64
12/64
12/64
13/63

Rear Passenger 
13/64
12/64
12/64
13/64

I triple checked those values on each tire. Anyone see a trend? 

Last time tire pressure was checked was at 3,500 miles, in ~68 degree weather, set to 50psi. After rotating, I checked the pressure again with outside temperature at 78psi, and the tires were all at 49psi. I filled them up to 50psi. 

I will be measuring tread depth and tire pressure again at 10,500 miles.


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## obermd (Mar 3, 2012)

XtremeRevolution said:


> Rotated tires today at 7012 miles and also measured them. These are the measurements I took before the tire was moved.
> 
> Front Driver:
> 12/64
> ...


Are the locations before or after you rotated the tires? From the fact that the edges are worn in the front I would guess before. Assuming I'm correct the trend I see here is that front tires wear on the edges first and rear tires wear in the center. Also, based on mileage and the original tread depth you will need to replace your tires between 30,000 and 35,000 miles, which is exactly where I would expect given that OEM tires all seem to wear out just before a 3 yr/36,000 mile lease ends, forcing the leasor to replace the tires and return a car with brand new tires.


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## XtremeRevolution (Jan 19, 2012)

obermd said:


> Are the locations before or after you rotated the tires? From the fact that the edges are worn in the front I would guess before. Assuming I'm correct the trend I see here is that front tires wear on the edges first and rear tires wear in the center.


The locations are before I rotated the tires. I measured them right after removing them from the car.


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## obermd (Mar 3, 2012)

Given that XtremeRevolution's tires have worn through 1/32 in 7000 miles, the OEM tires must also have slightly softer rubber compound than the retail version. There are 5/32 of usable tread depth on the OEM tires. On the retail tires there are 8/32 of usable tread depth. Assuming the same rate of tread wear, this would only work out to 56,000 miles before retail tire replacement. However, the retail tires are waranteed for 65,000 miles. In order to get the additional 9,000 miles the retail tires must have a slightly harder tread compound.


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## CruzeEcoBlueTopaz (Jan 5, 2012)

I would like to say that with 26k miles on my 2012 eco the tire tread looks as even and thick as the day I rolled off the lot and im not even exaggerating.


I have a question. Do tires wear as much if mostly driven on the highway as compared to mainly city driving ? Im assuming the less turning and stop - go acceleration the longer the life of the tire.


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## XtremeRevolution (Jan 19, 2012)

CruzeEcoBlueTopaz said:


> I would like to say that with 26k miles on my 2012 eco the tire tread looks as even and thick as the day I rolled off the lot and im not even exaggerating.
> 
> 
> I have a question. Do tires wear as much if mostly driven on the highway as compared to mainly city driving ? Im assuming the less turning and stop - go acceleration the longer the life of the tire.


I can assure you that they've worn a significant amount, but to answer your question, yes, they do wear more during mainly city driving, which is what I do. 



obermd said:


> Given that XtremeRevolution's tires have worn through 1/32 in 7000 miles, the OEM tires must also have slightly softer rubber compound than the retail version. There are 5/32 of usable tread depth on the OEM tires. On the retail tires there are 8/32 of usable tread depth. Assuming the same rate of tread wear, this would only work out to 56,000 miles before retail tire replacement. However, the retail tires are waranteed for 65,000 miles. In order to get the additional 9,000 miles the retail tires must have a slightly harder tread compound.


Could be. I'm guessing GM didn't want these tires to last us very long...


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## CruzeEcoBlueTopaz (Jan 5, 2012)

I have no doubt they have worn but the condition they are still in is very impressive. Im certain these tires will keep spinning safely for me well into the 60k+


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## XtremeRevolution (Jan 19, 2012)

CruzeEcoBlueTopaz said:


> I have no doubt they have worn but the condition they are still in is very impressive. Im certain these tires will keep spinning safely for me well into the 60k+


With the amount of pure highway driving you do, I'd say that's probably easily within reach. I forgot that you didn't do much of any city driving, lol.


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## XtremeRevolution (Jan 19, 2012)

70AARCUDA said:


> ...when you plot *tread-depth *_vs._ *milage*, what sort of equation and corellation coefficient (R-squared) do you get?
> 
> ...I got a decent linear equation, but that was with _combined_ city (40%) & highway (60%) driving...with city driving involving lots more turning-corners which tends to wear front-tire shoulders.


Not enough data for me to come to any real conclusions just yet. The tread depth gauge only measures in increments of 1/64", and even that's too large of an increment to measure based on how little the tread depth changes. After another 7,000 miles, I might have some data we can use.


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## NBrehm (Jun 27, 2011)

obermd said:


> Given that XtremeRevolution's tires have worn through 1/32 in 7000 miles, the OEM tires must also have slightly softer rubber compound than the retail version. There are 5/32 of usable tread depth on the OEM tires. On the retail tires there are 8/32 of usable tread depth. Assuming the same rate of tread wear, this would only work out to 56,000 miles before retail tire replacement. However, the retail tires are waranteed for 65,000 miles. In order to get the additional 9,000 miles the retail tires must have a slightly harder tread compound.


Maybe, maybe not. could also just be Xtreme's driving style and road conditions. I have 30K on my car (mostly highway) and still have 5/32 on the tires. Having to hit the brakes alot wears tires out alot faster than just cruising down the highway. Assuming the same tire wear I can expect to get close to 75,000 miles out of the OEM tires (which kinda sucks because I don't like them but don't want to waste them).


Oh and for the record I am using manufacturers recommended tire pressure.


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## NBrehm (Jun 27, 2011)

Actually correction, I have about 20K on the tires, I had snows on for 10K, but still a significant difference


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## XtremeRevolution (Jan 19, 2012)

NBrehm said:


> Actually correction, I have about 20K on the tires, I had snows on for 10K, but still a significant difference


20k sounds more legitimate for that tread depth. The testing I've seen shows that the tires become unsafe after the tread gets to less than 4/32", with the legal limit being at 2/32", so you'll probably get another 5-10k out of them before they need replacing.


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## 70AARCUDA (Nov 14, 2010)

XtremeRevolution said:


> Not enough data for me to come to any real conclusions just yet. The tread depth gauge only measures in increments of 1/64", and even that's too large of an increment to measure based on how little the tread depth changes. After another 7,000 miles, I might have some data we can use.


...just for an idea of what you 'might' get, below is the *tread wear *_vs._ *milage* equation I've gotten for the OEM Goodyear RSA's on my 2009 Vibe at 40 psi (vs. stock 32 psi) for 27K miles driven:

*MILES ~ (9.745 - X)/0.000085;* RR = 0.59 (rather _poor_ correllation!)

where:

*MILES* = miles driven
*X* = tread depth, in 32's of an inch (*10*/32 for brand new RSA tire).

...which, roughly_ approximates _as *10K-miles *per each *1/32"* of tread wear.


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## NBrehm (Jun 27, 2011)

XtremeRevolution said:


> 20k sounds more legitimate for that tread depth. The testing I've seen shows that the tires become unsafe after the tread gets to less than 4/32", with the legal limit being at 2/32", so you'll probably get another 5-10k out of them before they need replacing.


Why do you think they are unsafe at 4/32"? I wouldn;t try drive them in the snow but in the dry and the rain there should be no problems (comparatively speaking anyway)


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## obermd (Mar 3, 2012)

NBrehm said:


> Why do you think they are unsafe at 4/32"? I wouldn;t try drive them in the snow but in the dry and the rain there should be no problems (comparatively speaking anyway)


As long as you're driving dry roads only, tires should be good down to 2/32". If you drive in rain or snow the ability of the tire tread to redirect/drain water and snow away from the tire surface basically ends at 4/32". The minimum depth of standing water on most paved road surfaces is about 2/32", which means that at 4/32" or lower tire simply doesn't have enough tread depth to overcome the surface tension of the water on the tread plus the water on the road to channel the water away from the tire surface and into the the tread channels. Snow works in a similar manner because the friction and compression caused by the tire actually melts the surface of the snow.


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## XtremeRevolution (Jan 19, 2012)

NBrehm said:


> Why do you think they are unsafe at 4/32"? I wouldn;t try drive them in the snow but in the dry and the rain there should be no problems (comparatively speaking anyway)


See below.



obermd said:


> As long as you're driving dry roads only, tires should be good down to 2/32". If you drive in rain or snow the ability of the tire tread to redirect/drain water and snow away from the tire surface basically ends at 4/32". The minimum depth of standing water on most paved road surfaces is about 2/32", which means that at 4/32" or lower tire simply doesn't have enough tread depth to overcome the surface tension of the water on the tread plus the water on the road to channel the water away from the tire surface and into the the tread channels. Snow works in a similar manner because the friction and compression caused by the tire actually melts the surface of the snow.


^ What he said. 

I've read a few studies done on this where they actually tested stopping distance and hydroplaning resistance, and it was noted that 4/32" is the lowest one can go and still maintain a safe wet stopping distance. Anything below 4/32" will start to significantly degrade wet stopping distance. By the time you're at 2/32", you're better off pulling over during a heavy rain storm and just waiting it out.


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## 70AARCUDA (Nov 14, 2010)

...agree 100% -- if there ain't enough "room" in the grooves for the water to channel out from under the tire, then the tire is gonna have to "ride" on TOP of that water, and that spells _"...*hydroplaning*..!"_


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## NBrehm (Jun 27, 2011)

Whats the latest tread depth?


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## XtremeRevolution (Jan 19, 2012)

NBrehm said:


> Whats the latest tread depth?


Post 45:

http://www.cruzetalk.com/forum/27-f...th-log-max-sidewall-pressure-5.html#post97486


Currently at 7,800 miles, so it will be a while before I get to check again.


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## rmay635703 (Jun 25, 2012)

ChevyCruzeLTZ said:


> First I'm going to say I'm gonna wath this thread because IMHO you cannot run 50 psi in a cruze without excessive wear to the center of the tread over time.


This statement is pure sillyness, how exactly does that 50psi stretch the metal bands in the tire?

The shape of your tire is determined by the steel inside, you can't stretch the steel, nor can you burst a decent condition tire with high pressure. (32psi tires burst somewhere beyond 200psi, the same is likely true of 40 & 50psi rated tires) Tires normally wear unevenly because of the weight, angle and suspension characteristics.

Anyway YOU CAN damage your suspension or rims if you hit some massive road hazard however and YOU CAN wear out your suspension faster.

My experience since I started driving is that tires generally last longer if you run that at higher than normal pressures as listed on the placert on the door jam. I have run over 1,000,000 miles at 44-60psi in all my tires on a variety of vehicles, no blowouts.

My experience has been to NOT rotate tires on a brand new vehicle until the wear pattern is visible.

On my 010 cobalt the front which I kept in the 40's for ride purposes wore more in the middle of the tire and wore more quickly than the rears which wore minimally and evenly at 50psi.

I swapped tires and now keep 50psi up front and high 30's to mid 50's on the rear depending on what fuel economy I want and how much weight it back there. The rears seem to wear the sides more at lower pressures, my plan is to "catch up" the worn down the middle fronts by having them in the rear. The tire pressure in the rear tires seems to have much less affect on my MPG than the fronts so I now have a plan for the rest of the usable life of the cobalt.

On my cobalt 50psi = 50mpg so I tend to keep it that way whenever possible.

Cheers
Ryan


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## XtremeRevolution (Jan 19, 2012)

Got the new measurements done today at just shy of 10,500 miles. As a comparison point, here are the old numbers. I have color coded them this time so you can get an idea of which tire went where and how it changed. To clarify, these measurements were taken from the outside going inward, and they are labeled according to where the tire was located _before _it was rotated. 

Front Driver:
12/64
13/64
13/64
12/64

Front Passenger:
12/64
13/64
13/64
12/64

Rear Driver
13/64
12/64
12/64
13/63

Rear Passenger 
13/64
12/64
12/64
13/64

Here are the new numbers. This time around, I decided to check and record tire pressure as well. Tire pressure the last time I checked was at ~7,500 miles. They were 50psi with outside temps at 78 degrees. The new measurements were done at 84 degrees outside temps. I have marked the changes in bold. 

Front Driver
48psi
*12/64*
12/64
12/64
13/64

Front Passenger
47psi
*12/64*
12/64
12/64
*12/64*

Rear Driver
47psi
12/64
*12/64
12/64*
12/64

Rear Passenger
47psi
12/64
*12/64
12/64*
12/64

It's interesting that the front driver tire didn't wear as much on the edges, but I suspect it was barely on the edge of reading 13/64 instead of 12/64. I had to measure in various locations, and the measurements were a bit difficult to take as there were a few places that measured 13/64 while most measured 12/64, so I simply used the most common measurement along the tire. I get the impression that the next measurement at 14,000 miles will report minor changes. In either case, this is 10,500 miles down at 50psi and completely even tire wear throughout. 

The total data is still quite limited. To be honest, 3 samples is hardly something we can make any useful conclusions from with regard to predicted total tire life. However, based on the information so far, I'd expect to be able to go a minimum of 40,000 miles on these tires before needing replacements. That wouldn't be bad for an OEM all-season with less usable tread than the retail version of the tire. Unfortunately, even 1/64" is not a fine enough increment with which to measure short-term changes in tire depth. 

If my driving habits stay the same, I should be able to report my tread depth at 14,000 miles in 2 months.

One more interesting thing to note is changes in tire pressure. While my outside temperature increased by 6 degres F, my tire pressure decreased by 3psi over the course of 2 months/3500 miles.


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## obermd (Mar 3, 2012)

When I had Discount Tire rotate my tires at 10,000 miles they measured the tread depth on all four tires. The two rear tires were at 7/32 in all tread channels and the front tires were 8/32 in all tread channels. Guage was mechanical and only measured in 1/32 increments. I ran my tires at 40 PSI for the first 7,000 miles and then switched to 45 PSI. The two tires measuring 7/32 were on the front the entire time I was at 40 PSI.


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## XtremeRevolution (Jan 19, 2012)

I tried a mechanical gauge and it was simply too difficult to get an accurate reading. Plus, 1/32" increments were just way too large. I can believe the car started with 7/32 though.


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## NBrehm (Jun 27, 2011)

The PSI change is normal, tires do "leak" air, normally about a pound a month. With the higher PSI you are running I wouldn't be surprised to 2 or even 3 PSI a month find it's way out. I have one other question, how often do you hit the highway? That is where the treadware would be seen the most in the center. If you are on the brakes a lot in stop and go traffic it will certainly help keep the treadware more even (and much faster), since you will continually compress the tires. I do alot of highway driving and I run my tires at 38PSI cold, at 35,000 miles there is already almost a 2/32 tread difference in the center.


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## XtremeRevolution (Jan 19, 2012)

NBrehm said:


> The PSI change is normal, tires do "leak" air, normally about a pound a month. With the higher PSI you are running I wouldn't be surprised to 2 or even 3 PSI a month find it's way out. I have one other question, how often do you hit the highway? That is where the treadware would be seen the most in the center. If you are on the brakes a lot in stop and go traffic it will certainly help keep the treadware more even (and much faster), since you will continually compress the tires. I do alot of highway driving and I run my tires at 38PSI cold, at 35,000 miles there is already almost a 2/32 tread difference in the center.


I don't technically drive on the highway a lot. Most of my driving is "in-town" although much of it is 45-55mph wooded roads. I get stuck in stop and go traffic for about 30 minutes a day out of a total of 2 hours of driving.The last 2000 miles, I did significantly more highway driving than usual as I had family in town and we put about 1000 miles of highway driving on the car at that time. It didn't really show. 

Sent from my Bulletproof_Doubleshot using AutoGuide.Com Free App


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## XtremeRevolution (Jan 19, 2012)

NBrehm said:


> The PSI change is normal, tires do "leak" air, normally about a pound a month. With the higher PSI you are running I wouldn't be surprised to 2 or even 3 PSI a month find it's way out. I have one other question, how often do you hit the highway? That is where the treadware would be seen the most in the center. If you are on the brakes a lot in stop and go traffic it will certainly help keep the treadware more even (and much faster), since you will continually compress the tires. I do alot of highway driving and I run my tires at 38PSI cold, at 35,000 miles there is already almost a 2/32 tread difference in the center.


Wait a minute, I just realized something. 

These tires started off with somewhere around 7/32" of tread life with the safe limit being 4/32" (anything above that has measured significant reduction in hydroplaning resistance and increased wet stopping distance) and legal limit being 2/32". You're telling me that by running only 3psi above placard pressure, you've worn off 2/32" of tread in the center? That's more than half of the usable "safe" tread you have available on the stock tires. 2/32" is a lot of difference with what's arguably "close enough" to stock pressure over 35k miles. 

Is it common for people to wear down the centers of tires that badly just from highway driving? I can't say I've ever had it happen before, and I drove almost exclusively on the highway with my last car.


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## obermd (Mar 3, 2012)

NBrehm said:


> The PSI change is normal, tires do "leak" air, normally about a pound a month. With the higher PSI you are running I wouldn't be surprised to 2 or even 3 PSI a month find it's way out. I have one other question, how often do you hit the highway? That is where the treadware would be seen the most in the center. If you are on the brakes a lot in stop and go traffic it will certainly help keep the treadware more even (and much faster), since you will continually compress the tires. I do alot of highway driving and I run my tires at 38PSI cold, at 35,000 miles there is already almost a 2/32 tread difference in the center.


Something else is going on. I have never had the center of my tires wear first and until my Cruze ECO (which I'm running 10 PSI over the placard) I have always run 5 PSI over placard. I've had edges wear due to alignment issues but never the center of the tread. Radial tires shouldn't buldge in the center as long as the cold PSI is below the max PSI molded into the sidewall.


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## NBrehm (Jun 27, 2011)

Don't know what to tell you, centers are 3/32 and sides are 5/32. Between 28,000 and 35,000 I have seen some very significant tire wear. I'm sure some of it has been the hot weather, but they are wearing faster the further they get down in tread. I put the car on the alignment rack and everything is spec, steering/suspension parts all checked out. When you think about cruising on the highway the tire is more or less unloaded for a lot of the time, so it rides on the same part of the tire the majority of the time. When you are cornering, stopping and accelerating you are putting the tire under more load and in multiple directions, which will change wear characteristics since the contact patch will change as the load changes.


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## XtremeRevolution (Jan 19, 2012)

Where are you measuring the center? The tire has 5 tread ridges. I ignore the absolute center one because the slits are more shallow. I measure between the slits of the two outer and two inner ridges.

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## obermd (Mar 3, 2012)

XtremeRevolution said:


> Where are you measuring the center? The tire has 5 tread ridges. I ignore the absolute center one because the slits are more shallow. I measure between the slits of the two outer and two inner ridges.


I was unaware the middle tread channel was shallower than the outer two channels on each side.


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## XtremeRevolution (Jan 19, 2012)

obermd said:


> I was unaware the middle tread channel was shallower than the outer two channels on each side.


The actual center tread isn't shallower, but rather the slits inside it are shallower so the gauge doesn't go down as far, resulting in a more shallow reading.

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## NBrehm (Jun 27, 2011)

Measurements are
LF 5,4,3,3,5
RF 4,3,3,3,5
RR 5,3,3,3,5
LR 5,4,3,4,5

If you can think of something that would make the center of the tires wear that isn't air pressure related and not a bad strut ( there is no cupping) I'm all ears.


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## obermd (Mar 3, 2012)

NBrehm said:


> Measurements are
> LF 5,4,3,3,5
> RF 4,3,3,3,5
> RR 5,3,3,3,5
> ...


I saw this pattern on my Transport one time. If I remember correctly it was the camber on the front wheels. This is not a normal pattern and I needed shims on the front suspension to correct it as the Transport didn't have any adjustment for it.


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## bartonmd (Jun 30, 2011)

NBrehm said:


> Measurements are
> LF 5,4,3,3,5
> RF 4,3,3,3,5
> RR 5,3,3,3,5
> ...


It is air pressure. I've run the tires usually right between max and sticker, and every tire on everything I've ever owned is lower in the middle than the sides, when it's replaced. The Trailblazer and Caprice are 2 that were really bad. The Caprice would do it at 38psi (44psi tires), and the TB would do it at 40PSI really badly, but only to a semi-acceptable level at 37psi. When I got rid of the OEM tires for the TB, they were on the wear bars in the center, and had 3/32" to go to the wear bars at the sides. The 80PSI tires on my Cummins would do that really bad, as well, when they were anywhere near 80. I settled on 60F/50R (empty), and they wear about even.

When I went 10-ply on the tires for the TB, I had a pretty good chat with a tec rep from BFG about pressures. I had been running 37psi in the 10-plies on the TB, and they were wearing the edges like crazy. Called, and they have a chart for the pressure curves of each tire, with how much weight at what pressure makes them wear correctly. Turned out that the correct pressure for those tires on my TB was 45PSI (max sidewall 80). So, I put them at 60 for a ~4k to get the centers to wear more, so they'd be even, then put them back to 45, and they've been wearing evenly ever since. More than that and they wear the centers, and less and they wear the sides. It's really a question of sidewall strength vs. tread strength/width vs. pressure vs. weight. A strong sidewall will hold a lot of vertical pressure, and you need to have enough pressure in the tire for the center to put as much pressure against he ground as the sidewall puts. That amount of pressure is directly related to the weight put on the tire. ETA: basically, a stronger sidewall than stock = higher than stock pressure, and a wider tire than stock = lower pressure. So if you go big/strong + wide, you usually end up at about factory presssure.

Having said that, these tires will be less sensitive to over-pressure than full size tires. They have a relitively short sidwall, which sort of makes up for some sidwall strength (adds to it), and they are pretty narrow, so there's not a whole lot of deflection that'll happen. Plus, they don't have enough tread depth to get REALLY out of kilter by the end of the tire life.

I am surprised, though, that nobody has corrected Extreme, yet, about the reason that OEMs have less tread depth on their tires. It's not a cost saving measure. Tires with less tread depth have less rolling resistance, and get better fuel mileage for the EPA/CAFE numbers. I know it because my whole family and a bunch of friends are in the automotive industry, but I thought this was somewhat common knowledge?

Mike


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## obermd (Mar 3, 2012)

Why do tires with less tread depth have less rolling resistance? I understand older tires have less rolling resistance as the rubber hardens with age.


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## XtremeRevolution (Jan 19, 2012)

The problem I have with all this is, assuming this IS pressure related, my tires would be in a really bad place right now having been run at 50-51psi this whole time even given some of the more city-related driving I'm doing. 

What bothers me the most is bartonmd is saying that Nbrehm's tire wear is pressure related. However, those tires are run just 3psi above placard pressure and are wearing worse than mine are at 15psi above placard pressure. I have a hard time believing an 8% increase in tire pressure will completely throw off the tire wear pattern to the point where his centers will wear out that badly.

It was claimed that the tires compressing is what caused the difference in tire wear since he's on the highway and I'm driving city, but you have to remember that at 50-51 psi *cold*, my tires don't really have a whole lot of compression, and I drive for fuel economy so I don't exactly take corners like a madman or brake hard. You'd think by 10,500 miles, I'd have *some *indicator of abnormal tire wear due to those pressures, but so far, I don't, and the same can be said of the tires on my two other cars.


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## bartonmd (Jun 30, 2011)

XtremeRevolution said:


> The problem I have with all this is, assuming this IS pressure related, my tires would be in a really bad place right now having been run at 50-51psi this whole time even given some of the more city-related driving I'm doing.
> 
> What bothers me the most is bartonmd is saying that Nbrehm's tire wear is pressure related. However, those tires are run just 3psi above placard pressure and are wearing worse than mine are at 15psi above placard pressure. I have a hard time believing an 8% increase in tire pressure will completely throw off the tire wear pattern to the point where his centers will wear out that badly.


I've found, and it makes sense to me, that the more highway the tires do, the more they will be prone to wearing in the center with higher pressures, and it doesn't have to be all that much higher. Cornering and driving in the city (extra weight transfer to the front under braking, etc.) wears the sides more than the center, and centripetal force on the tread at high speeds will have more of an affect on the center wearing than the sides.


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## Skraeling (May 30, 2012)

XtremeRevolution said:


> This is true, and should indicate that there's really nothing wrong with doing it this way. I will probably find myself a good set of uni-directional tires to replace the current ones when they wear down or rot.


as an addition, awd cars are recommended strict front to back back to front only.


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## bartonmd (Jun 30, 2011)

obermd said:


> Why do tires with less tread depth have less rolling resistance? I understand older tires have less rolling resistance as the rubber hardens with age.


They are lighter, and 1# rotating is worth 10# static. Tires flex as they go around. The less rubber thickness you are compressing, the less you're heating up the rubber, the less energy is being used to flex the rubber, the less rolling resistance you have.

Mike


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## bartonmd (Jun 30, 2011)

XtremeRevolution said:


> It was claimed that the tires compressing is what caused the difference in tire wear since he's on the highway and I'm driving city, but you have to remember that at 50-51 psi *cold*, my tires don't really have a whole lot of compression, and I drive for fuel economy so I don't exactly take corners like a madman or brake hard. You'd think by 10,500 miles, I'd have *some *indicator of abnormal tire wear due to those pressures, but so far, I don't, and the same can be said of the tires on my two other cars.


To your edit:

He has 3x the mileage you have on your tires. I usually don't notice anything at first, but it seems like the less tread the center has, the more it flexes out at speed, the faster the center wears. 

Also, this is not a motorycle tire. Regardless of whether you corner like a mad man or not, car tires still work on slip angles.

Mike


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## obermd (Mar 3, 2012)

Skraeling said:


> as an addition, awd cars are recommended strict front to back back to front only.


My Montana AWD's owners manual showed a cross pattern. There are some sports cars that use unidirectional tires that require front/rear only. My Fiero GT could only be left/right rotation as the front tires were smaller than the rear tires. It really depends on the car.


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## Skraeling (May 30, 2012)

obermd said:


> My Montana AWD's owners manual showed a cross pattern. There are some sports cars that use unidirectional tires that require front/rear only. My Fiero GT could only be left/right rotation as the front tires were smaller than the rear tires. It really depends on the car.


and tread pattern I guess as well.

edit: **** you said that already.


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## XtremeRevolution (Jan 19, 2012)

bartonmd said:


> I've found, and it makes sense to me, that the more highway the tires do, the more they will be prone to wearing in the center with higher pressures, and it doesn't have to be all that much higher. Cornering and driving in the city (extra weight transfer to the front under braking, etc.) wears the sides more than the center, and centripetal force on the tread at high speeds will have more of an affect on the center wearing than the sides.


I'd be more inclined to believe that his driving solely on the highway had significantly more to do with his tire wear than his tire pressure did. That, I can wholeheartedly believe now that I think about it more. We'd all be going absolutely nuts if we had to keep that close track of our tire pressures to make sure they aren't even 3psi above placard. That would mean the difference between 1 month's time out here in the midwest. Fill them up to 35psi with on a 60 degree day, and take a guess as to what they'll be on an 85 degree day. If we live our lives assuming that every minuscule (let's be honest, 8% is minuscule) change in tire pressure can make or break our wear patterns, we'd all go crazy, but you certainly won't find me going out there every other week to check my pressure when the temperatures change. 

You said his wear patterns were pressure related. I'm just not buying it, and don't take that as disrespectful or rude. 



bartonmd said:


> To your edit:
> 
> He has 3x the mileage you have on your tires. I usually don't notice anything at first, but it seems like the less tread the center has, the more it flexes out at speed, the faster the center wears.
> 
> ...


I was referring more to the hard cornering having a greater wear on the edges. I know for a fact that constant hard cornering will scrub tire edges significantly more than just rolling around them gently. 

I would understand not noticing anything at first, but I'm now 1/32" and 10,500 miles down and they're still very even. Perhaps at 3,000 miles, one could say that there aren't enough miles on the tires to make any real judgment, but is 10,500 miles really considered "at first?"

Regardless, some of these questions are the reason why I created this thread. I'm making the numbers available every 3,500 miles so everyone can keep track of the wear patterns, and I'm also measuring with a decent amount of precision so I can catch any changes almost immediately. 



bartonmd said:


> They are lighter, and 1# rotating is worth 10# static. Tires flex as they go around. The less rubber thickness you are compressing, the less you're heating up the rubber, the less energy is being used to flex the rubber, the less rolling resistance you have.
> 
> Mike


I don't disagree with that at all, but I will ask how great of an effect that really has, especially compared to a reduction in rolling resistance as a consequence of tire pressure.


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## bartonmd (Jun 30, 2011)

XtremeRevolution said:


> I'd be more inclined to believe that his driving solely on the highway had significantly more to do with his tire wear than his tire pressure did. That, I can wholeheartedly believe now that I think about it more. We'd all be going absolutely nuts if we had to keep that close track of our tire pressures to make sure they aren't even 3psi above placard. That would mean the difference between 1 month's time out here in the midwest. Fill them up to 35psi with on a 60 degree day, and take a guess as to what they'll be on an 85 degree day. If we live our lives assuming that every minuscule (let's be honest, 8% is minuscule) change in tire pressure can make or break our wear patterns, we'd all go crazy, but you certainly won't find me going out there every other week to check my pressure when the temperatures change.
> 
> You said his wear patterns were pressure related. I'm just not buying it, and don't take that as disrespectful or rude.
> 
> ...


FWIW, the full temperature range of tires is ~10% pressure difference, from "cold" on a cold day to "hot" on a hot day. You also have to figure that he's 8-10% above recomended all the time, not just when it's not. Yes, if you do a lot of city driving, it will hide the results of being a little over-pressure, that would not be hidden by a lot of straight highway driving. Yes, hard cornering wears the sides more than the center, but any cornering wears the sides more than the center, because of the slip angles in the tire's contact with the pavement. The center has basically none, the outside is being dragged along, and the inside is slipping in the direction of motion (like the "spinning the tires" direction). In fact, there are different "perfect" pressures for wear, depending on what the duty cycle of the car is, but they just pick a pressure somewhere in the middle. So if he does all highway, his ideal pressure will be a little on the low side of spec (for wear only), and if you do a lot of city, your pressure will be a little on the high side of spec.

As I said, this vehicle should be a little more resistant to it, given the type and size of tires we have, and it took 60,000 miles and 10/32 of tread wear to see a 3/32 difference between the side and center on something that I ran 8% above sticker. So yes, I'd say that 10k miles and 1/2-1/32" is still "at first."

Also, you said you are still flat, which is true, but you didn't start out flat. You started out with the "front" (green and red, IIRC) tires being 1/32 higher in the center than the sides, and now they're even across the tire; so you've worn at least 1/64" more in the center than the sides, even with your duty cycle, and this short amount of mileage, with this little amount of tread wear. I'll tell you that with only 3-4/32 of useably tread life, measuring in 32ndths of an inch is probably a bit on the large side to get any real useable data.

Yes, the rolling resistance does get lower at higher pressures, but so does traction. Even if they had tires that would wear well at 50psi on this car (which they don't), they still have to pass the stopping deceleration test, as well as the tests the mags run them through. Nobody's going to want a smallish sportyish car that pulls .6g on a skid pad, or stops from 60 in 150'. Let's not even get into the "corvair-esque" media storm of people sliding off corners in the rain with these tires at 50PSI. The contact patch at that pressure, with these tires, in this car, doesn't lend itself to performance of any kind other than gas mileage. I did try it in mine for a couple days last summer, one of them in the rain, and it did NOT perform well AT ALL.

Mike


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## XtremeRevolution (Jan 19, 2012)

bartonmd said:


> Also, you said you are still flat, which is true, but you didn't start out flat. You started out with the "front" (green and red, IIRC) tires being 1/32 higher in the center than the sides, and now they're even across the tire; so you've worn at least 1/64" more in the center than the sides, even with your duty cycle, and this short amount of mileage, with this little amount of tread wear. I'll tell you that with only 3-4/32 of useably tread life, measuring in 32ndths of an inch is probably a bit on the large side to get any real useable data.
> 
> Yes, the rolling resistance does get lower at higher pressures, but so does traction. Even if they had tires that would wear well at 50psi on this car (which they don't), they still have to pass the stopping deceleration test, as well as the tests the mags run them through. Nobody's going to want a smallish sportyish car that pulls .6g on a skid pad, or stops from 60 in 150'. Let's not even get into the "corvair-esque" media storm of people sliding off corners in the rain with these tires at 50PSI. The contact patch at that pressure, with these tires, in this car, doesn't lend itself to performance of any kind other than gas mileage. I did try it in mine for a couple days last summer, one of them in the rain, and it did NOT perform well AT ALL.
> 
> Mike


I didn't start out flat? You sure? At 4,000 miles, all of my tires were dead even at 13/64". Keep in mind the mileage at which this was all measured. There was additional wear on the front tires on the shoulders, and additional wear on the rear tires on the centers, at 7,000 miles. After rotating them and driving them for 3,500 miles, that all balanced out and I'm virtually flat across the tread again, having lost 1/64" of tread depth in ~7,000 miles. 

Like I said, this is what this thread is for. So far, they're wearing flat. We'll see what happens. I'm an honest guy and will report exactly what the tires report. 

As far as deceleration, there was another thread where I went into this in great detail. The NHTSA and Goodyear tests done with varying tire pressures indicate that stopping distance is generally unaffected by tire pressure (unless you start to reduce it significantly). I've posted the articles several times across different threads on this forum. While you do indeed reduce contact patch on the road, you increase pressure on that given contact patch, so it's not exactly as though you're suddenly riding on bicycle tires. 

The following article highlights some of the information:
TIRE PRESSURE SURVEY AND TEST RESULTS

Now, they only went up to 35psi, but it doesn't take a genius to deduct that the reduction in contact patch reduces exponentially as tire pressure increases. There's a significantly bigger difference going from 15psi to 25psi than there is going from 25psi to 35psi, and even less going from 35psi to 45psi. Assuming these trends continue the way they are in an exponentially decreasing degree, you're going to need a bit more than "my family has worked in the automotive industry" to back up a claim that suddenly, stopping distance and cornering traction decreases dramatically. You're claiming a reduction from ~.85gs to .60gs in the skidpad an increase from 122 feet to 150 feet in stopping distance, and with all due respect, I'd like some proof. I too ran my tires at varying pressures in the rain this year to test the difference in stopping ability and they wouldn't still be at 50psi if I noticed a compromise.

I can bring up all of the articles if absolutely necessary, but I figured you've been here long enough to where you should have seen them. It might also be worth noting that police cruisers also run their Goodyear Eagle RS-As at max sidewall pressures, partially due to weight, but there are other factors involved. Again, these articles were posted before.

Honestly, I'm a bit annoyed that this has to be discussed a 3rd time about the exact same arguments that have already been beaten to death. Feel free to respond in the below thread, where many people have gone over this exact same topic. 

http://www.cruzetalk.com/forum/27-fuel-economy/5733-tire-psi-max-mpgs.html

This current thread was created so I could report my tread depth every 3,500 miles on rotations to determine wear patters at max sidewall pressure. It was created as a result of the above thread, not as an extension of it.


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## bartonmd (Jun 30, 2011)

XtremeRevolution said:


> I didn't start out flat? You sure? At 4,000 miles, all of my tires were dead even at 13/64". Keep in mind the mileage at which this was all measured. There was additional wear on the front tires on the shoulders, and additional wear on the rear tires on the centers, at 7,000 miles. After rotating them and driving them for 3,500 miles, that all balanced out and I'm virtually flat across the tread again, having lost 1/64" of tread depth in ~7,000 miles.
> 
> Like I said, this is what this thread is for. So far, they're wearing flat. We'll see what happens. I'm an honest guy and will report exactly what the tires report.
> 
> ...


Oh, you're right. The comparison was between 7k and 10k. I sort of speed-read the thread, and it statistically makes much more sense to compare current to start, so I hadn't considered you'd be comparing neighboring samples, directly, without also comparing to start.

While I am an Engineer, the comment about my family being Engineers in the auto industry was about the reason I thought it was common knowledge that manufacturers use lower tread height tires as OEM for fuel mileage. The stopping and lateral G numbers, I had thought, were outlandish enough that you'd pick up on the sarcasm. However, at 50PSI, I was sliding around enough at the pace that my wife drives the car, that I wouldn't have let her drive it like that. She drives everything like it's a stock car, though, so that may be a little different than you have tested, based on your previous statements (I'm an upper 1/3 Intermediate rider on the track, knee down on 3/4 of the turns depending on the track, and while it's not hard for me to keep up with her down a twisty road, I have a good time following her). It's not as bad as the Trailblazer was (before the center wore and it gave a full contact patch, again), but like I said, this car is probably less succeptable to it because of the lower profile tires. I found it to be very unsafe as you pick the pace up. The understeer went from slowly creeping up and easy to ride the traction line at 35-37psi, to boom-gone (and stabilitrac kicks on, big-time) at 50psi. Threshold braking was the same thing. At the sticker PSI, you can theshold brake a little bit without the ABS kicking on, but at 50psi, not only did the ABS come on much sooner, but it was next to impossible to threshold brake without kicking the ABS on. Yes, you are trading contact patch for ground pressure, but that only works until you've got enough heat in the contacting material that the boundry layer starts to melt. This is THE reason for wide tires for drag racing. Heat. The other thing we have on the street (particularly out in the country, where I live) is sand/gravel on the road. Tires at lower pressure are MUCH more able to keep a good amount of traction with a little sand or gravel on the road. You get cut down the contact patch at the same time as making the tire less able to flex, it's much easier to get the tires to lose traction on sand/rocks and bumpy roads.

Police cars are completely, 100% different than what we're talking about. They're not only over-loaded all the time, but they also keep them up in order to not bend wheels and such, curb jumping. RS/As are also Z-rated, and have a much stronger sidewall than what we have, and will need a higher pressure in the center to match the sidewalls.

I believe you'll report the correct findings. As I said, though, if you're reporting in 32nds of an inch, it's going to take more than 10k for you to really see a defined difference. Regardless of your personal feelings or annoyance, I started replying to this thread to answer NBrehm's question about his wear at 3x the mileage you have, and correct you on why the tires come with less tread from the OEM.

Mike


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## XtremeRevolution (Jan 19, 2012)

bartonmd said:


> Oh, you're right. The comparison was between 7k and 10k. I sort of speed-read the thread, and it statistically makes much more sense to compare current to start, so I hadn't considered you'd be comparing neighboring samples, directly, without also comparing to start.
> 
> While I am an Engineer, the comment about my family being Engineers in the auto industry was about the reason I thought it was common knowledge that manufacturers use lower tread height tires as OEM for fuel mileage. The stopping and lateral G numbers, I had thought, were outlandish enough that you'd pick up on the sarcasm. However, at 50PSI, I was sliding around enough at the pace that my wife drives the car, that I wouldn't have let her drive it like that. She drives everything like it's a stock car, though, so that may be a little different than you have tested, based on your previous statements (I'm an upper 1/3 Intermediate rider on the track, knee down on 3/4 of the turns depending on the track, and while it's not hard for me to keep up with her down a twisty road, I have a good time following her). It's not as bad as the Trailblazer was (before the center wore and it gave a full contact patch, again), but like I said, this car is probably less succeptable to it because of the lower profile tires. I found it to be very unsafe as you pick the pace up. The understeer went from slowly creeping up and easy to ride the traction line at 35-37psi, to boom-gone (and stabilitrac kicks on, big-time) at 50psi. Threshold braking was the same thing. At the sticker PSI, you can theshold brake a little bit without the ABS kicking on, but at 50psi, not only did the ABS come on much sooner, but it was next to impossible to threshold brake without kicking the ABS on. Yes, you are trading contact patch for ground pressure, but that only works until you've got enough heat in the contacting material that the boundry layer starts to melt. This is THE reason for wide tires for drag racing. Heat. The other thing we have on the street (particularly out in the country, where I live) is sand/gravel on the road. Tires at lower pressure are MUCH more able to keep a good amount of traction with a little sand or gravel on the road. You get cut down the contact patch at the same time as making the tire less able to flex, it's much easier to get the tires to lose traction on sand/rocks and bumpy roads.
> 
> ...


What you're saying makes sense. Believe me, if there's a significant compromise, I'll do everything to avoid that. I firmly believe that you're better off stopping faster and being able to avoid a situation better even if someone rear ends you, because then their insurance company covers it, but if you hit someone else, it's your fault. I'll wait for the next heavy rainfall and go out in an empty parking lot to see how the Cruze handles. 

To clarify, I'm reporting in 1/64" of an inch increments with a digital tire depth gauge. 

The annoyance was mostly that another thread went completely off track. I understand why you replied. It's not that big of a deal. 

Thanks for the correction on why they come with less tread from the OEM.


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## XtremeRevolution (Jan 19, 2012)

While we're still here, something I've done a lot of research into is hydroplaning resistance. Traction aside, wouldn't a higher pressure and lower contact patch improve hydroplaning resistance? 

I know there are very many people over on the cleanmpg forums that run very high pressures in their tires (some as high as 80psi). I'll ask around and see if they have any testing data.


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## bartonmd (Jun 30, 2011)

XtremeRevolution said:


> While we're still here, something I've done a lot of research into is hydroplaning resistance. Traction aside, wouldn't a higher pressure and lower contact patch improve hydroplaning resistance?
> 
> I know there are very many people over on the cleanmpg forums that run very high pressures in their tires (some as high as 80psi). I'll ask around and see if they have any testing data.


I would think it wouldn't be much, but there may be some... I could see a smaller contact patch from a narrower tire really helping it, but the patch, itself, being smaller on the same width tire shouldn't cause a huge difference, I wouldn't think. Then, there's also the question of how deep you're talking, though... I don't see it making any difference on deep puddles, but I could see it making a little bit of difference in a hard rain with 1/2" of water over the whole road. I haven't had any hydroplaning in this vehcle, as it is, so I don't know if the little bit of difference in potential would matter.

Mike


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## XtremeRevolution (Jan 19, 2012)

bartonmd said:


> I would think it wouldn't be much, but there may be some... I could see a smaller contact patch from a narrower tire really helping it, but the patch, itself, being smaller on the same width tire shouldn't cause a huge difference, I wouldn't think. Then, there's also the question of how deep you're talking, though... I don't see it making any difference on deep puddles, but I could see it making a little bit of difference in a hard rain with 1/2" of water over the whole road. I haven't had any hydroplaning in this vehcle, as it is, so I don't know if the little bit of difference in potential would matter.
> 
> Mike


This is the article that led me to ask that question:

Tire Tech Information - Air Pressure vs. Wet Performance

Unfortunately, there is very little information out there regarding anything other than standard tire pressures. The article by tirerack shows a distinct improvement in hydroplaning resistance going from 25 to 35psi. I'm wondering if that benefit is compounded going with even higher pressures. 

I rarely hit large puddles out where I live, but as I'm sure you know, we do get some pretty heavy rainfalls with 1/2" of water on the road. It's the latter condition that I'm concerned with.


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## bartonmd (Jun 30, 2011)

Have I mentioned that I really, really hate how VerticalScope has to change links to other sites to AutoGuide searches?

To the question, I honestly do now know for sure. Like I say, it makes sense that there would be some, but a lot of hydroplaning resistance is tread width per weight, and tread design/depth, when you're around normal pressures. There are enough different things at play, and it's a complex enough set of circumstances, that I'd like to see some real, scientific testing on it if it has been done...

I just sort of try and get around the circumstances by not running any tires until they're done. I usually buy a set of tires, run them 2/3 of the way down, sell them on CList for $50-$150 depending on what they're worth, and buy a new set. $50-$75 of tread life lost in the transaction is 1/4 of my deductable, so it's cheap insurance.

Mike


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## NBrehm (Jun 27, 2011)

bartonmd said:


> I've found, and it makes sense to me, that the more highway the tires do, the more they will be prone to wearing in the center with higher pressures, and it doesn't have to be all that much higher. Cornering and driving in the city (extra weight transfer to the front under braking, etc.) wears the sides more than the center, and centripetal force on the tread at high speeds will have more of an affect on the center wearing than the sides.


Exactly the point I was trying to make. with regard to air pressure Vs wet traction the only tidbit I have is with higher tire pressure you will be transferring more weight to the ground (less sidewall flex) which with good wet tires could possibly help, but with tires that aren't so good in the wet will probably make you more prone to losing traction.


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## obermd (Mar 3, 2012)

Unless GM has really changed how their suspensions work since the 1990 and 2002 model years something else is going on other than long distance driving on straight roads. I have driven over 400,000 miles on sets of tires rated for 50,000 to 80,000 miles, driven at least 95% of those miles before replacing the tires, and have never seen the tread wear pattern you're seeing. Until this past June I have always run my tires at 5 PSI cold over the door placard. In June I switched to 10 PSI over. Another reason I think something besides pressure is going on with NBrem's Cruze is that he said he started seeing more rapid tread wear after 28,000 miles. In my experience this is a sign that the rubber is starting to decay.


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## obermd (Mar 3, 2012)

bartonmd said:


> They are lighter, and 1# rotating is worth 10# static. Tires flex as they go around. The less rubber thickness you are compressing, the less you're heating up the rubber, the less energy is being used to flex the rubber, the less rolling resistance you have.
> 
> Mike


That makes sense. Sidewall flex is a vertical motion and vertical doesn't help MPG.


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## XtremeRevolution (Jan 19, 2012)

obermd said:


> Unless GM has really changed how their suspensions work since the 1990 and 2002 model years something else is going on other than long distance driving on straight roads. I have driven over 400,000 miles on sets of tires rated for 50,000 to 80,000 miles, driven at least 95% of those miles before replacing the tires, and have never seen the tread wear pattern you're seeing. Until this past June I have always run my tires at 5 PSI cold over the door placard. In June I switched to 10 PSI over. Another reason I think something besides pressure is going on with NBrem's Cruze is that he said he started seeing more rapid tread wear after 28,000 miles. In my experience this is a sign that the rubber is starting to decay.


Tire decay is one of the biggest reasons I'm running such a high pressure. Less rolling resistance means less heat, means less decay.

Sent from my Bulletproof_Doubleshot using AutoGuide.Com Free App


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## obermd (Mar 3, 2012)

XtremeRevolution said:


> Tire decay is one of the biggest reasons I'm running such a high pressure. Less rolling resistance means less heat, means less decay.


Tire decay is more a function of absolute age than mileage. Unused tires that have been sitting on the shelf for several years aren't safe to use. I wonder when NBrehm's tires were manufactured.


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## XtremeRevolution (Jan 19, 2012)

obermd said:


> Tire decay is more a function of absolute age than mileage. Unused tires that have been sitting on the shelf for several years aren't safe to use. I wonder when NBrehm's tires were manufactured.


I recall going through many articles on this topic, some of which were related to truck tires, and others for regular cars. The concept was that the constant flexing of the sidewall creates significant amounts of heat, which causes irreversible damage to the tire compound, thus increasing the likelihood of a blowout. 

Perhaps the technical term is not decay, but the research on the topic is out there. 

One way you can tell is by keeping an eye on tire pressure variations between cold hot (after you've driven a while, especially at highway speeds).

Sent from my Bulletproof_Doubleshot using AutoGuide.Com Free App


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## obermd (Mar 3, 2012)

It does make sense that mileage wear and tear will contribute to tire aging. I still think NBrehm's tires are older that he realizes.


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## bartonmd (Jun 30, 2011)

FWIW, I did a lot of research on this, and talked to several tire manufacturers, when I got a set of tires from onlinetires.com that had 1 tire 4 years old, 1 tire 3 years old, and 2 tires 2 years old. All the manufacturers said that as long as they were in a warehouse, and hadn't had and mold release worn off of them, they essentially hadn't aged at all. I guess the mold release also seals the rubber from the air, and stops it from drying out. 

Unless they've been run at a low pressure or over-loaded and way overheated, or unless they sit for years after they're been run, passenger car tires will be worn out before they're degraded from age. 6 years old is apparently when the mfgs say they should be replaced, or at the very least, inspected.

He can get the date from his tires. It's molded into the sidewall. 4 numbers. week-week-year-year. The tires on my '11 ECO are the 20th week of 2011, or 6 weeks before I got the car.

Mike


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## XtremeRevolution (Jan 19, 2012)

bartonmd said:


> FWIW, I did a lot of research on this, and talked to several tire manufacturers, when I got a set of tires from onlinetires.com that had 1 tire 4 years old, 1 tire 3 years old, and 2 tires 2 years old. All the manufacturers said that as long as they were in a warehouse, and hadn't had and mold release worn off of them, they essentially hadn't aged at all. I guess the mold release also seals the rubber from the air, and stops it from drying out.
> 
> Unless they've been run at a low pressure or over-loaded and way overheated, or unless they sit for years after they're been run, passenger car tires will be worn out before they're degraded from age. 6 years old is apparently when the mfgs say they should be replaced, or at the very least, inspected.
> 
> ...


Mike, 

I agree and have also found the same in my research. I posted a lengthy thread regarding this topic. You can find it in my signature in my blog. 

I even found the referenced video, which everyone should watch:

Dangerous Tires - YouTube


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## CruzeEcoBlueTopaz (Jan 5, 2012)

My 2012 eco is at 45k miles at 50k im replacing spark plugs, engine air filter , cabin air filter and i will post pictures of each also i will post a pic of my tire tread and mesasure it as well.


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## coinneach (Apr 10, 2012)

I bumped my tires to 44 psi at 1500 miles and measured the tread depth at four places on each tire (outsides and two inners). They were all 7mm. Yesterday, a bit over 5000 miles, I measured them again. Still 7mm straight across.


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## NBrehm (Jun 27, 2011)

obermd said:


> Another reason I think something besides pressure is going on with NBrem's Cruze is that he said he started seeing more rapid tread wear after 28,000 miles. In my experience this is a sign that the rubber is starting to decay.


tires we're manufactured in Feb 2011, all 4 have the same DOT stamp so there is no way they are decaying. And again, the car has been checked and is mechanically fine, no alignment or suspension issues. The only thing different then stock is the tire pressure and I started seeing the difference about 5,000 miles after I pumped it up. I check them at every oil change. I also only rotate front to back on the car so unless all 4 wheels have the same suspension issues there should be an anomoly where at the very least 1 side is wearing alot faster. Apart from the tread depth they have pretty even wear for 36,000 miles


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## andrewm2002 (Jul 27, 2011)

XtremeRevolution said:


> Second, these TPC tires will wear down significantly faster than their retail counterpart. I'm not sure who is going to buy an ECO car specifically for fuel economy to save money and actually want to get only half the life out of their tires. I also don't believe that the difference between 7/32" and 10/32" of tread depth will make a notable difference in road noise and handling characteristics. GM simply went cheap here and it's not the first time.


I don't work for GM or Goodyear. I do work for one of the top 5 tire manufactures in the world. The tires on our cars were designed with work with the suspension design. OE tires are actually designed to dampen some of the ride flaws the automaker engineers couldn't get out. Back in the day automakers would put the cheapest tires they could get on there.. it just isn't like that anymore. 

Besides.. we don't know the rubber compound used... if it's a harder compound than the replacement tires.. it very well may last as long. 

There is no problem whatsoever cross rotating tires (unless they are directional.) Whoever said that just didn't want to do it.

As for wear.. depending on the design of the tire they may not wear AS unevenly at 50 psi vs a traditional design. (new designs incorporate a continuous nylon strip around the tire for a flatter contact patch) They will wear in the center faster though.


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## XtremeRevolution (Jan 19, 2012)

New measurements taken at 14,000 miles. As a comparison point, here are the old numbers. I have color coded them as before so you can get an idea of which tire went where and how it changed. To clarify, these measurements were taken from the outside going inward, and they are labeled according to where the tire was located *before *it was rotated. 

Front Driver
48psi
12/64
12/64
12/64
13/64

Front Passenger
47psi
12/64
12/64
12/64
12/64

Rear Driver
47psi
12/64
12/64
12/64
12/64

Rear Passenger
47psi
12/64
12/64
12/64
12/64

Here are the new numbers. 

Front Driver
48psi
12/64
12/64
12/64
12/64

Front Passenger
47psi
12/64
12/64
12/64
12/64

Rear Driver
47psi
12/64
12/64
12/64
*12/64*

Rear Passenger
47psi
12/64
12/64
*11/64*
12/64

1/64" increments are not small enough to show a difference in 3,500 miles, but that's how often I rotate, so that's how often I report. I will note, most of my 12/64" measurements last time were closer to 13/64" but still showed up on the gauge as 12/64". This time, they were closer to 12/64" even. I suspect that by 15,000 miles, they cross from the low 12.xx/64" range to the high 11.xx/64" range. 

1/32" per 15,000 mile wear is what I would truthfully expect out of these tires at 50psi with my kind of driving. Note, the above also included lots of highway driving to Detroit and Lordstown and back to Chicago, which added up to about 900 miles of pure highway driving. That amount (25%) of highway driving did not have any adverse wear effects on these tires. 

Assuming these tires will continue to wear at the same rate as they have been, I can expect to get another 30,000 miles out of them (for a total of 45,000 miles) before I hit 4/32" of tread depth, which is my "safe" limit. 4/32" has been tested as the threshold for wet traction before it begins to measurably degrade. I can push it to 60,000 miles if I don't mind compromising wet traction to replace them at 3/32", and if I was dirt poor and couldn't afford tires, I could push that to 75,000 miles before they hit the legal limit of 2/32". That said, I cannot say whether or not they will actually wear at the same rate for the rest of their usable life, but the numbers so far are starting to look more conclusive. 

What should be noted is the fact that this is primarily city driving. According to my highway/city split, calculated based on average speed per tank of gas, this has been achieved with 74% city, 26% highway driving.


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## obermd (Mar 3, 2012)

Just had my tires rotated at 14,972 miles. Same Discount Tire I always use. Measured tread depth on all four tires was 7/32", probably with their mechanical tread depth tool. This represents no measurable tread wear since the first check at 1,500 miles.

I asked at Discount Tire about tread wear and was told that for the first half of a tire's life it wears very slowly. At some point it will wear down to a softer rubber compound and then the wear rate will be noticably faster. After thinking about it for a while I realized I have seen this type of wear rate change on the Bridgestones I always ran on my vans.

When I rotated at 10,000 miles I set the tire pressures to 45 PSI as measured by the TPMS. This morning my TPMS reported 39 PSI all around. I'll set them back to 45 PSI this weekend.


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## unitednations161 (Mar 13, 2011)

I have 45k on my car, Running tire pressure at 47 psi for its life. The centers are wore more then the outsides. But granted I don't rotate tires, only every oil change. I took it today to get winter tires on it, and the guys at the tire shop were out there bit**ing about the air I had in them. Saying cant this guy read, and told me im ruining my tires.


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## obermd (Mar 3, 2012)

unitednations161 said:


> I have 45k on my car, Running tire pressure at 47 psi for its life. The centers are wore more then the outsides. But granted I don't rotate tires, only every oil change. I took it today to get winter tires on it, and the guys at the tire shop were out there bit**ing about the air I had in them. Saying cant this guy read, and told me im ruining my tires.


Which tires are on your Cruze? If the Goodyear FuelMax Assurance then the guys at the tire store are the ones who can't read. They are rated at 51 PSI. Inflating past the door placard pressure, as long as you're below the sidewall pressure is a matter of personal choice and driving style.


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## Aussie (Sep 16, 2012)

Tyres should not be run in the reverse direction at rotation, as was mentioned earlier. My tyre supplier showed me a tyre he had taken off another car and it wasn't pretty. Tyre was exploded is the best way I can describe it, the steel belt was coming away right around the tyre.


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## obermd (Mar 3, 2012)

Aussie said:


> Tyres should not be run in the reverse direction at rotation, as was mentioned earlier. My tyre supplier showed me a tyre he had taken off another car and it wasn't pretty. Tyre was exploded is the best way I can describe it, the steel belt was coming away right around the tyre.


This is tire dependent. Most passenger tires don't care which way they spin. There are some tires that do care. You can tell by looking at the tread. Unidirectional tread on a tire is a sure indicator not to cross rotate the tires.


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## XtremeRevolution (Jan 19, 2012)

unitednations161 said:


> I have 45k on my car, Running tire pressure at 47 psi for its life. The centers are wore more then the outsides. But granted I don't rotate tires, only every oil change. I took it today to get winter tires on it, and the guys at the tire shop were out there bit**ing about the air I had in them. Saying cant this guy read, and told me im ruining my tires.


Yeah, you definitely need to keep your tires rotated. What kind of driving do you usually do? I keep mine at 50psi, but my driving is at least 70% in-town, where the sides will wear down more due to all the turning I do. From what I've seen, people wear down the insides of their tires a lot when driving only on the highway regardless of what tire pressure they use.


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## NBrehm (Jun 27, 2011)

If all 4 tires are worn in the center then rotating them wouldn't have made any difference. In fact rotating tires has a very negligible impact on the center.


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## XtremeRevolution (Jan 19, 2012)

NBrehm said:


> If all 4 tires are worn in the center then rotating them wouldn't have made any difference. In fact rotating tires has a very negligible impact on the center.


Rotating has an impact on the outside, which by association has an impact on the center. That said, I didn't ask for a clarification if he was referring to just two or all four of his tires, which I should have.


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## sciphi (Aug 26, 2011)

I've put about 33k miles onto the OEM Goodyears. They appear to be wearing evenly with regular rotations and running 45 PSI front, 42 PSI rear. I'd guess they have another 15k miles before they're at the wear bars.


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## unitednations161 (Mar 13, 2011)

obermd said:


> Which tires are on your Cruze? If the Goodyear FuelMax Assurance then the guys at the tire store are the ones who can't read. They are rated at 51 PSI. Inflating past the door placard pressure, as long as you're below the sidewall pressure is a matter of personal choice and driving style.




Well they are wearing in the center more then the outsides. I do mostly rural driving, with quite a bit highway miles. Small town as well. Yes they are the OEM goodyear fuelmax. I can take a picture if you would like. 45 thousand miles at 40-45psi are causing the centers to wear out faster then the sides, well something is causing it. ON THE FRONT ONLY. My back tires seem to be equal.


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## unitednations161 (Mar 13, 2011)

NBrehm said:


> If all 4 tires are worn in the center then rotating them wouldn't have made any difference. In fact rotating tires has a very negligible impact on the center.




Only the front two.


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## unitednations161 (Mar 13, 2011)

XtremeRevolution said:


> Yeah, you definitely need to keep your tires rotated. What kind of driving do you usually do? I keep mine at 50psi, but my driving is at least 70% in-town, where the sides will wear down more due to all the turning I do. From what I've seen, people wear down the insides of their tires a lot when driving only on the highway regardless of what tire pressure they use.



On my 84 eagle, the center tread is wore down just a tad bit more then the outsides, at 35 psi. My cruze front tires are way worse in the center though. But like i said Rear tires are even.


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## jadedgamerx (Nov 12, 2012)

XtremeRevolution said:


> What should be noted is the fact that this is primarily city driving. According to my highway/city split, calculated based on average speed per tank of gas, this has been achieved with 74% city, 26% highway driving.


Hi Xtreme, great thread! I'm catching up and only got here so far but will read the last couple pages soon. Would you be able to fill me in on how you find the City % based on average speed. I use fuelly and this has always been kind of an arbitrary thing for me ("Uh yeah... 25% highway! sounds good!") and I would like to have a more definitive system in place for this. Just looking for some tips on how you calculate or something you found to do so. Thank you!


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## XtremeRevolution (Jan 19, 2012)

jadedgamerx said:


> Hi Xtreme, great thread! I'm catching up and only got here so far but will read the last couple pages soon. Would you be able to fill me in on how you find the City % based on average speed. I use fuelly and this has always been kind of an arbitrary thing for me ("Uh yeah... 25% highway! sounds good!") and I would like to have a more definitive system in place for this. Just looking for some tips on how you calculate or something you found to do so. Thank you!


It's pretty simple, really. For me, a 20mph average speed is 100% city driving. If you're averaging less than that, you're practically crawling. This is very close to what EPA would use for the car in the "city" driving conditions. A 60mph average speed is 100% highway driving. Anything above that is excessive speed and will result in a drop in fuel economy over the EPA rating. If I remember correctly, the EPA rating used to be run at 55mph with a certain percentage of error factored in, so this also works well. 

We then take the average speed. If my average speed is 40mph, that's right in between 20mph and 60mph, so that's 50% city driving. If my average speed is 30mph, that's 75% city driving. 

Generally speaking, you can calculate your percentage of *city *driving using the following formula:

1 - (average speed - 20)/40

If our average speed is 35mph...
1 - (35 - 20)/40
1 - (15)/40
1 - 0.375 (at this point, 37.5% is our percentage of highway driving)
0.625 (this is our percentage of city driving)


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## jadedgamerx (Nov 12, 2012)

XtremeRevolution said:


> It's pretty simple, really. For me, a 20mph average speed is 100% city driving. If you're averaging less than that, you're practically crawling. This is very close to what EPA would use for the car in the "city" driving conditions. A 60mph average speed is 100% highway driving. Anything above that is excessive speed and will result in a drop in fuel economy over the EPA rating. If I remember correctly, the EPA rating used to be run at 55mph with a certain percentage of error factored in, so this also works well.
> 
> We then take the average speed. If my average speed is 40mph, that's right in between 20mph and 60mph, so that's 50% city driving. If my average speed is 30mph, that's 75% city driving.
> 
> ...


Thank you sir!

Also curious, are you running your winter tires at max rated sidewall and tracking tread wear at all? I was considering picking up the same tread measuring device you have (it looks like a general tools one from Amazon) and doing the same.


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## XtremeRevolution (Jan 19, 2012)

jadedgamerx said:


> Thank you sir!
> 
> Also curious, are you running your winter tires at max rated sidewall and tracking tread wear at all? I was considering picking up the same tread measuring device you have (it looks like a general tools one from Amazon) and doing the same.


I am running my winter tires at 40PSI. Max sidewall on those is 44PSI. In this case, I want a bit more of a footprint on packed snow and ice so I won't be running the at max sidewall, and I won't be measuring them either. 

I like the tread depth gauge that I bought. I consider it a good investment as all of the other ones I've seen are of poor quality, consistency, and accuracy. This one gets the job done well.


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## obermd (Mar 3, 2012)

Which tread depth guage do you have?


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## XtremeRevolution (Jan 19, 2012)

obermd said:


> Which tread depth guage do you have?


Central Tools 3S401 Digital Tire Tread Depth Gage : Amazon.com : Automotive


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## jadedgamerx (Nov 12, 2012)

XtremeRevolution said:


> I am running my winter tires at 40PSI. Max sidewall on those is 44PSI. In this case, I want a bit more of a footprint on packed snow and ice so I won't be running the at max sidewall, and I won't be measuring them either.
> 
> I like the tread depth gauge that I bought. I consider it a good investment as all of the other ones I've seen are of poor quality, consistency, and accuracy. This one gets the job done well.


I am also running mine somewhere around 39-40 PSI, although based on the way tires leak and the mileage on them so far over the last month with MN temps I wouldn't be surprised if I'm closer to 36 at this point, will check them this weekend. They are a noisy bunch but they grip well! Looking forward to further updates on this thread once the warm weather resumes. Very helpful information.


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## Beaker (Mar 21, 2012)

Getting my tires rotated today. Had them check the tread depth. 7-8/32nds on all four tires. Left rear had a little uneven wear but I'm having them check the alignment and fix if necessary. At 18,300 miles.


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## DrVette (Dec 6, 2011)

My tread depth @ 26,500mi = 7/32" even wear all groves
t/p 50# since 4k mi~

Tread @ 3890# was .254"F & .260"R
Dunno how to convert to /32" anyone?


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## XtremeRevolution (Jan 19, 2012)

DrVette said:


> My tread depth @ 26,500mi = 7/32" even wear all groves
> t/p 50# since 4k mi~
> 
> Tread @ 3890# was .254"F & .260"R
> Dunno how to convert to /32" anyone?


My experience has been similar. I just went out and measured tread depth again. My silly self didn't realize that I was measuring the cross-sectional tread depth instead of the circumferential water channels in my old measurements. No matter; the main point was to determine wear patterns. 

In any case, I went out and measured my front driver tire just now. I am 150 miles overdue for a tire rotation at this point. They'll be done this weekend. 

Tread depth was, from inside to outside, correctly measured this time, 

8/32"
8/32"
8/32"
7/32"

That should flatten out when I put them on the back for the next 3,500 miles. I'm at 22k miles on the odometer right now. These are legitimately 70-75k mile tires (assuming they don't dry rot by then) at max sidewall. No clue how long they should last someone at 35PSI.


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## XtremeRevolution (Jan 19, 2012)

Alright, time to start this anew, for a couple of reasons. First, I started measuring in the circumferential water channels for tread depth, and second, I had one of the tires replaced last year in the fall when my Cruze was rear-ended. 

So, here are the numbers from today's tire rotation. This is where the tires were before I rotated them. Measurements are from the inside to the outside. ~22k miles. 

Driver Rear:
16/64
16/64
16/64
16/64

Driver Front:
16/64
16/64
16/64
15/64

Passenger Rear (new tire):
18/64
18/64
18/64
18/64

Passenger Front:
15/64
15/64
15/64
15/64


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## Stock 87 (Sep 8, 2011)

Stock 87 said:


> Just to add a little to the tread thread. I have an ECO manual with 26,000 miles, I always run my tires at 5 psi over recomended. The Dealer rotates them (I don't know how) every 7000 miles. As of now I cannot tell that there has been any wear to the tires. Also expecting to get at least 80k before they need to be replaced





XtremeRevolution said:


> Gooooood luck with that 80k mile expectation. I highly doubt you'll achieve that. The tires that came on the car had only 7/32" of tread depth when new. The retail Goodyear Assurance tires (the ones you have on now are TPC spec) have 10/32" of tread depth.


Well I just rolled 60k. Tires have been 5psi over the entire time. I will get at least 80k miles from these tires... not even a doubt in my mind. I'd have to say that there is no less than 7/32" of tread on all four tires with complete even wear.


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## XtremeRevolution (Jan 19, 2012)

Stock 87 said:


> Well I just rolled 60k. Tires have been 5psi over the entire time. I will get at least 80k miles from these tires... not even a doubt in my mind. I'd have to say that there is no less than 7/32" of tread on all four tires with complete even wear.


Well, it may be worth noting that my original statement was made almost a year ago, at a time during which I incorrectly believed that the tires had less tread on them from the factory (being TPC Spec tires) than the retail version do. 

How did you determine that there is no less than 7/32" of tread left? By that math, you would be able to go 120k miles on these tires before you hit 4/32", and I know for a fact that even our high-mileage highway-only drivers don't get that much life out of these tires. I can believe 70k or 75k if you want to creep a little under 4/32", but you begin to severely compromise wet handling and hydroplaning resistance as you drop below 4/32". 

All of the measurements I take are with a digital tire depth gauge, since the mechanical ones I've tried are horribly inaccurate.


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## ErikBEggs (Aug 20, 2011)

For the sake of bragging rights...

18" All Season Michelin Pilots - LTZ - 40,000 miles was 8/32, 8/32, 7/32, 7/32. 

60,000 miles?! Go Michelin man...

I do a fair bit of city driving as well. My split on fuelly is 50 / 50. The average speed on my commute is a paltry 28 mph, but I get on the open road a bit on the weekends and during the summer.


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## 13Cruze (Mar 12, 2013)

DrVette said:


> My tread depth @ 26,500mi = 7/32" even wear all groves
> t/p 50# since 4k mi~
> 
> Tread @ 3890# was .254"F & .260"R
> Dunno how to convert to /32" anyone?


To convert decimal to 32nds, divide your decimal number by 0.03125
0.254"/0.03125= 8.128/32, just over 8 32nds
0.260"/0.03125= 8.32/32, about 8 1/3 32nds

To convert to 64ths, divide by 0.015625

The number typically used for final depth before replacing your tires is 4/32, or in decimal, 0.125"


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## Vetterin (Mar 27, 2011)

Checked mine again last weekend. 5/32 on every tire after 36,700 miles.


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## Stock 87 (Sep 8, 2011)

XtremeRevolution said:


> Well, it may be worth noting that my original statement was made almost a year ago, at a time during which I incorrectly believed that the tires had less tread on them from the factory (being TPC Spec tires) than the retail version do.
> 
> How did you determine that there is no less than 7/32" of tread left? By that math, you would be able to go 120k miles on these tires before you hit 4/32", and I know for a fact that even our high-mileage highway-only drivers don't get that much life out of these tires. I can believe 70k or 75k if you want to creep a little under 4/32", but you begin to severely compromise wet handling and hydroplaning resistance as you drop below 4/32".
> 
> All of the measurements I take are with a digital tire depth gauge, since the mechanical ones I've tried are horribly inaccurate.


I didn't post this to pee in your Cheerios. 
I figured I must have one of the higher milage Eco's and wanted to throw up a quick update. 

Car is driven 97% highway, 140 miles a day during the week. Seeing how my tires have been wearing, I think 100k miles is actually possible. I will run them until I hit the wear bars.


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## XtremeRevolution (Jan 19, 2012)

Stock 87 said:


> I didn't post this to pee in your Cheerios.
> I figured I must have one of the higher milage Eco's and wanted to throw up a quick update.
> 
> Car is driven 97% highway, 140 miles a day during the week. Seeing how my tires have been wearing, I think 100k miles is actually possible. I will run them until I hit the wear bars.


I'm not sure where you perceived offense at anything I said, but thanks for the update. 

I'm not entirely certain what depth the wear bars are at, but I would not recommending wearing them down to 2/32". There are countless publications on the safety risks in wearing your tires down that low. 

Panic Stopping: How Much Tread Depth Do You Need?


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## Stock 87 (Sep 8, 2011)

I have no idea what depth the wear bars are at either, they are there for a reason though. Tire companies do testing to figure out when the tire no longer maintains acceptable performance. I'm sure this is taken into consideration when setting minimum tread depth. Just saying X depth is the cutoff doesn't fly with me, due to the different compounds and tread designs used today. That would be like saying all makes of tires have the same perfomance up until the "cutoff". We all know this isn't true. 

I also find that having low tire pressure has a much greater effect on wet and snow handling that low/shallow tread. I was absolutely blow away with the perfomance of these tires this past winter. Even though they are "street" tires with 50k miles on them at the time, they never gave me the slightest issue in snow and ice. I'm talking stopped going up a 5% grade on solid ice in a traffic jamb on the highway. Every time i'd let the clutch out my ass would pucker and the car would pull out like it was all wheel drive. Un-real actually

The car is driven almost exclusively highway, and my driving style doesn't lend itself to panic stops. I never even use the brakes due to the following distances I maintain.


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## obermd (Mar 3, 2012)

Most tires have the wear bars at 2/32", which is the legal minimum tread depth in the US.


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## XtremeRevolution (Jan 19, 2012)

obermd said:


> Most tires have the wear bars at 2/32", which is the legal minimum tread depth in the US.


Unfortunately, the tires have long exhausted their safe usability by the time they reach 2/32" of tread depth.


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## obermd (Mar 3, 2012)

XtremeRevolution said:


> Unfortunately, the tires have long exhausted their safe usability by the time they reach 2/32" of tread depth.


Very true.


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## coinneach (Apr 10, 2012)

You mean what's legal isn't necessarily safe, and people have to use their brains?

THAT'S UNAMURRICAN!


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## Gravity (Apr 6, 2013)

XtremeRevolution said:


> Unfortunately, the tires have long exhausted their safe usability by the time they reach 2/32" of tread depth.


That really depends what your doing with the tire at 2/32 you have lost almost all hydroplaning resistance and forget driving in the winter. but if its June/July your normally pretty safe. with that said i personally change mine at 4 32nds depending on the time of year. I live in a pretty poor county and the general replacement policy around here is when it pops or when the steel shows.


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## obermd (Mar 3, 2012)

Gravity said:


> That really depends what your doing with the tire at 2/32 you have lost almost all hydroplaning resistance and forget driving in the winter. but if its June/July your normally pretty safe. with that said i personally change mine at 4 32nds depending on the time of year. I live in a pretty poor county and the general replacement policy around here is when it pops or when the steel shows.


You start losing hydro planing resistance anytime the tread drops below 4/32. It's completely gone by 2/32.


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## XtremeRevolution (Jan 19, 2012)

Gravity said:


> That really depends what your doing with the tire at 2/32 you have lost almost all hydroplaning resistance and forget driving in the winter. but if its June/July your normally pretty safe. with that said i personally change mine at 4 32nds depending on the time of year. I live in a pretty poor county and the general replacement policy around here is when it pops or when the steel shows.


Yep, hydroplaning is what I was referring to. The tests I've read show that you're safe down to 4/32" as far as hydroplaning resistance and stopping distance goes. Below that, your wet performance starts to degrade very rapidly. 3/32" is pushing it, and 2/32" is asking for trouble. Out here in Chicago (and in all of the midwest I imagine), we get some nasty flash storms that drop a lot of water very quickly. Get caught on the highway with 2/32" of tire left in one of those storms and you're better off pulling over and waiting the storm out.


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## Chris2298 (Aug 1, 2012)

If you're not throwing sparks when you do a burnout, you have PLENTY of tire left!


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## Gravity (Apr 6, 2013)

obermd said:


> You start losing hydro planing resistance anytime the tread drops below 4/32. It's completely gone by 2/32.


'

anytime theres tread left its never completely gone id drive around on a bridgestone with 2/32's left before i got in a car with cooper trendsetters on it. its all in the rubber tread depth helps evacuate standing water but the tread pattern/rubber compound is what gives you wet traction.


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## NBrehm (Jun 27, 2011)

Gravity said:


> '
> 
> anytime theres tread left its never completely gone id drive around on a bridgestone with 2/32's left before i got in a car with cooper trendsetters on it. its all in the rubber tread depth helps evacuate standing water but the tread pattern/rubber compound is what gives you wet traction.


That mostly true, remember water only compresses so far. Most tires at 2/32's, unless they have tons of sipes, will trap more water than they can compress to get to the pavement, hence the reason the sharp drop in hydroplaning resistance below 4/32's of an inch. Since channel width remains the same you cover the same area of water, but have less and less vertical distance for that water to "compress" into


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## Gravity (Apr 6, 2013)

NBrehm said:


> That mostly true, remember water only compresses so far. Most tires at 2/32's, unless they have tons of sipes, will trap more water than they can compress to get to the pavement, hence the reason the sharp drop in hydroplaning resistance below 4/32's of an inch. Since channel width remains the same you cover the same area of water, but have less and less vertical distance for that water to "compress" into


assuming the water cant escape and can only compress this is correct. any tire will hydroplane if the water is deep enough clearly more tread depth is better but to tell people its completely gone is a scare tactic to get them into buying new tires. there is nothing wrong with getting the full life out of your tires you just need to be aware that under 4/32s things go downhill and in some cases (hydroplaning resistance) they go downhill fast.


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## Blue Angel (Feb 18, 2011)

Actually, for practical purposes water is not compressible. What increases hydroplaning with worn tires is the grooves get shallower so their cross section is reduced, making it take more force (pressure) from the tire to evacuate a given amount of water in a given time.

This is the same concept as trying to pour the same jug of water through a large funnel and a small one. As long as the flow rate is low enough (vehicle speed) either funnel can do the job. As flow rate increases (higher vehicle speed) the smaller diameter funnel will start to back up while the larger one will still flow adequately.

When tire with low tread tries to evacuate water it can't do it effectively and the water backs up as speed increases. The backed up water exerts a higher and higher upward force (pressure) as water depth and/or speeds increase, eventually lifting the tire enough to cause traction loss.


Sent from AutoGuide.com Free App


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## XtremeRevolution (Jan 19, 2012)

25,311 miles

These are the tires' old locations, before they were rotated, from outside to inside.

The edge of the driver rear tire will wear flat in the next 3500 miles when it's on the front. Still at 50PSI. 

pass rear
15/64
15/64
15/64
15/64

pass front
17/64
17/64
17/64
17/64

driver front
15/64
15/64
15/64
15/64

driver rear
15/64
15/64
15/64
*16/64*


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## Blue Angel (Feb 18, 2011)

So it's taken you about 25,000 miles to wear 3/64ths off your tires? At this rate, you'll be at 4/32nds tread left at around 80,000 miles... according to this guy that's not going to happen:



XtremeRevolution said:


> Gooooood luck with that 80k mile expectation. I highly doubt you'll achieve that. The tires that came on the car had only 7/32" of tread depth when new. The retail Goodyear Assurance tires (the ones you have on now are TPC spec) have 10/32" of tread depth.




I read your post where you started measuring the main grooves instead of the actual tread blocks. You do know that the OE tire does come with 9/32nds tread, not 7/32nds right? Tire Rack:

Goodyear Assurance Fuel Max

The regular tire, as you noted, comes with 10/32nds. Was your starting tread depth of 7/32nds based on measuring the tread blocks, or did you read that spec somewhere?

So if you end up going 80k on these tires and still have 4/32nds tread left, do you plan to push them farther and see how much you can get out of them?

WRT tire pressure, I've always run slightly higher pressures up front on FWD cars since so much more of the car's weight is carried up front. I'm doing the same with my Eco, but I'm not keeping a detailed log for tire wear. I'm currently setting the tires at 49 F and 45 R, cold. I also have my front toe set as close to zero as possible, which may also reduce tire wear.

I'm currently at ~10k miles (16k kms) and haven't rotated them yet. I will try to get a tread depth gauge before rotating them and see how they're wearing.


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## ErikBEggs (Aug 20, 2011)

XtremeRevolution said:


> 25,311 miles
> 
> These are the tires' old locations, before they were rotated, from outside to inside.
> 
> ...


For some reason those seem fast... Those darn LRR things. I'm 7/32, 7/32, 8/32, 8/32 last checked at 38,000 miles


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## XtremeRevolution (Jan 19, 2012)

ErikBEggs said:


> For some reason those seem fast... Those darn LRR things. I'm 7/32, 7/32, 8/32, 8/32 last checked at 38,000 miles


Your measurements really don't mean anything unless you use a gauge with at least 1/64" accuracy. Those cheap manual gauges aren't really very accurate and definitely aren't valid for comparison purposes. A digital gauge would give you a much more accurate measurement. 

The LTZ tires are rated for 40k miles. Based on your measurements of 3/32" per 38,000 miles, you'd be getting at least double the mileage that they are rated for. My tires are rated for a 65k mile life, which as you'll see in my next post is actually almost exactly what I'm going to be getting. 



Blue Angel said:


> So it's taken you about 25,000 miles to wear 3/64ths off your tires? At this rate, you'll be at 4/32nds tread left at around 80,000 miles... according to this guy that's not going to happen:
> 
> 
> 
> ...


In response to this old post, I did realize that 4,098 miles of that reported mileage was actually driven on snow tires.


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## XtremeRevolution (Jan 19, 2012)

Rotated the tires today at 29,522 miles, 25,433 miles of which was driven on these tires (4,098 miles were on snow tires). Old location measurements, from outside to inside are as follows:

Passenger front: 
14/64
14/64
14/64
14/64

Passenger rear (this was the one replaced when I got rear ended):
16/64
16/64
16/64
16/64

Driver front:
14/64
14/64
14/64
14/64

Driver rear:
14/64
15/64
15/64
15/64

Still wearing almost perfectly flat across all 4. They were 5 PSI low when I measured them so I filled them back up to 50 PSI at 70 degrees F.

If we are to take the minimums at 14/64, we could deduct that I can get ~4250 miles per 1/64" of tread, or 8,500 miles per 1/32" of tread. I expect to have to replace these tires at somewhere between 55,000 and 60,000 miles once they wear close to 3/32". I'm not waiting till the legal limit of 2/32" to replace them.


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## Farmerboy (Sep 2, 2012)

I'm looking to replace my tires with current mileage at 54,327. I don't have a depth gauge but they are approaching the wear bars. My wife mostly runs this car so I want to keep them in good shape. One thing I have noticed is an increase in wet road mpg loss as the tires got less tread.


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## Farmerboy (Sep 2, 2012)

Just replaced my tires at 59,400 mi. Tread depth was at apr. 3/32. Tire Rack showed two different types of the FuelMax tires. One had 10/32 tread the other had only 9/32. The 10/32 weighed 23 lb to the 9/32 19lb. I chose the lighter one at $119. If they last like the original I will be happy.


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## XtremeRevolution (Jan 19, 2012)

Farmerboy said:


> Just replaced my tires at 59,400 mi. Tread depth was at apr. 3/32. Tire Rack showed two different types of the FuelMax tires. One had 10/32 tread the other had only 9/32. The 10/32 weighed 23 lb to the 9/32 19lb. I chose the lighter one at $119. If they last like the original I will be happy.


That's a fairly good length for these tires. Not bad. 

I don't really know what the stock tread depth is though but those should last a good while. I'll be replacing mine with 235 wide tires though when the time comes 

Sent from AutoGuide.com App


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## XtremeRevolution (Jan 19, 2012)

XtremeRevolution said:


> Rotated the tires today at 29,522 miles, 25,433 miles of which was driven on these tires (4,098 miles were on snow tires). Old location measurements, from outside to inside are as follows:
> 
> Passenger front:
> 14/64
> ...


I rotated my tires again today. It has been a while and I've missed two rotations. With the move, I simply haven't had time. In addition, I lost my tread depth gauge and bought an analog one that allows me to see 1/10ths of 1/32", which is far more accurate than the digital one that read every 1/64". So here it goes. Numbers first, then a review later. 

Current mileage: 44,938
Miles on snow tires: 7,418
Miles on OE LRR tires: 37,520

Passenger front: 
4.8/32
4.5/32
4.5/32
4.6/32

Passenger rear (the tire that was replaced at one point)
5.8/32
5.6/32
5.7/32
5.6/32

Driver front:
5.1/32
5.0/32
5.0/32
5.1/32

Driver rear:
5.0/32
5.0/32
5.1/32
5.3/32

One thing I want to make clear here is that I'm working with some extremely small numbers. 1/320th of an inch is difficult to measure accurately, so there will be some variation. In addition, it has been a while since I rotated my tires, and I don't see any evidence of significantly uneven wear. What I did see however is growing signs of dry rot as the rubber is starting to degrade and crack. They haven't been losing air, which is good, and I just made a 1,100 mile all-highway trip in the past week. 

To re-evaluate my wear patterns, I am now at approximately an average of 5/32" with 37,520 miles on these tires, or about 7,500 miles per 1/32" of tread depth. This is deviation from my previously calculated 8,500 miles per 1/32" of tread depth. However, I am also measuring with far more accuracy. If I am to replace them with 3/32" remaining, I will now be able to keep them for 52,520 miles. That said, I will probably get rid of them by the end of spring next year due to the dry rot and dropping tread depth. I'll see how they do once we start getting more heavy rain.


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## CruzeEcoBlueTopaz (Jan 5, 2012)

For comparison

Just crunching the numbers from my memory. My 2 sets of oem gy fm chvy eco tires rated for 65k warranty with a 9/32 tread depth allowed me an average of 87k miles with 2/32 remaining at approx 37-38 psi average ( 12,400 miles per 1/32 ) . My 1 set of oem gy fm eco tires rated for 65k with a 9/32 tread depth allowed me 70k miles with 1/32 remaining at 40-41 psi ( 8,750 miles per 1/32 ). 

My 4th and current set of oem gy fm chvy eco tires I plan on keeping at the reccommended 35psi and if my math is correct I should be able to reach 95k safe miles with 2/32 remaining... if so I will have some fairly positive data showing a longer lasting tire at the recommended tire pressure.


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## Blue Angel (Feb 18, 2011)

Interesting... looking forward to that CEBT.


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## XtremeRevolution (Jan 19, 2012)

CruzeEcoBlueTopaz said:


> For comparison
> 
> Just crunching the numbers from my memory. My 2 sets of oem gy fm chvy eco tires rated for 65k warranty with a 9/32 tread depth allowed me an average of 87k miles with 2/32 remaining at approx 37-38 psi average ( 12,400 miles per 1/32 ) . My 1 set of oem gy fm eco tires rated for 65k with a 9/32 tread depth allowed me 70k miles with 1/32 remaining at 40-41 psi ( 8,750 miles per 1/32 ).
> 
> My 4th and current set of oem gy fm chvy eco tires I plan on keeping at the reccommended 35psi and if my math is correct I should be able to reach 95k safe miles with 2/32 remaining... if so I will have some fairly positive data showing a longer lasting tire at the recommended tire pressure.


Generally speaking, higher pressures will increase tire life, not reduce it, and driving conditions make an enormous difference in tire wear. According to my fuelly records where I keep track of average speed to determine city/highway split, my driving has been 64% city/36% highway. Contrast this to your ~100% highway driving.

Some of the guys on the clean mpg forums were going up to 80psi and found that their tires weren't even half worn by the time they were too dry rotted to keep being used. Their reports of completely flat tire wear at those pressures is what spurred me to create this thread.


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## mcg75 (Mar 5, 2012)

XtremeRevolution said:


> Some of the guys on the clean mpg forums were going up to 80psi and found that their tires weren't even half worn by the time they were too dry rotted to keep being used. Their reports of completely flat tire wear at those pressures is what spurred me to create this thread.


It is truly scary how much dry rot I'm seeing on fairly new tires lately. 

It used to be that we would watch for this type of thing for older people who's biggest adventure was a grocery store trip once a week. 

Michelin seems to be the worst offender although I've seen some Firestone as well. 

When your tires were molded in 2012 and are dry rotting in 2014 without sitting around, something is wrong somewhere in the supply chain.


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## Blue Angel (Feb 18, 2011)

mcg75 said:


> When your tires were molded in 2012 and are dry rotting in 2014 without sitting around, something is wrong somewhere in the supply chain.


That, or the bean counters got a hold of Engineering and "worked out" a compromise that no longer caters to those who get more than 3-4 years out of a set of tires. Sounds like an environmental concern to me, if people are going to be throwing tires away before their time should be up.

To be fair, a little bit of surface cracking on the sidewals or shoulder is likely nothing more than a cosmetic issue. If it leaves belts exposed to the elements or results in rapid and uneven tread wear, that's a different story.


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## Eastwood (Nov 28, 2013)

Hey Xtreme, thanks for recording all this.

I glanced through the thread and didn't notice it anywhere, so sorry if this is old info, but are your tires the Goodyear Assurance FuelMax 255/55R17 94Vs?


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## XtremeRevolution (Jan 19, 2012)

Eastwood said:


> Hey Xtreme, thanks for recording all this.
> 
> I glanced through the thread and didn't notice it anywhere, so sorry if this is old info, but are your tires the Goodyear Assurance FuelMax 255/55R17 94Vs?


OEM Goodyear Assurance FuelMax 215/55/17, TPC spec.


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## carbon02 (Feb 25, 2011)

XtremeRevolution said:


> Central Tools 3S401 Digital Tire Tread Depth Gage : Amazon.com : Automotive


I realize this is an old thread, but I'm planning on buying a Tread Depth Gage for a Christmas gift. Amazon has one used, with damaged packaging for signficant savings. 

From what I understand, the gage itself is in a pretty nice case, did it ship additional packaging around that? If it's well protected do I take a chance in saving $22 buying slightly damaged packaging? 

I've done this before when the item has been enclosed in additional packaging and been very happy with the results. 

Anyone remember how this ships from Amazon?

Thanks-


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## carbon02 (Feb 25, 2011)

XtremeRevolution said:


> I lost my tread depth gauge and bought an analog one that allows me to see 1/10ths of 1/32", which is far more accurate than the digital one that read every 1/64"



Xtreme-

Could you comment on the packaging of the digital one you used to own? Was it shipped enclosed in additional packaging? Looking to save money buying a damaged box unit. 

Who makes the new analog one that reads 1/10th of 1/32nd?

Thanks


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## XtremeRevolution (Jan 19, 2012)

carbon02 said:


> Xtreme-
> 
> Could you comment on the packaging of the digital one you used to own? Was it shipped enclosed in additional packaging? Looking to save money buying a damaged box unit.
> 
> ...


Black rectangular case with hard foam cutout inside for the gauge and for two button cell batteries. Having to replace the batteries got annoying. 

Here's the new one I'm using now. 

http://www.amazon.com/gp/aw/d/B000EIDRD0?pc_redir=1414071091&robot_redir=1


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## XtremeRevolution (Jan 19, 2012)

I wanted to take the time to conclude this thread. The OE tires were replaced at 49,265 miles. 

Of that mileage, 9,128 miles were driven on snow tires, which means I got 40,137 miles out of these tires. 

The OE Goodyear tires were at 4.0-5.0/32" in tread depth, which was far from the legal limit. Fronts were closer to 4/32", rears were closer to 5/32", and I was due for a rotation. The reason I got rid of them was wet traction. It became compromised to the point where I was not comfortable using them. 

During that 40,137 miles, the tires were always at maximum sidewall pressure, and tire wear was within 0.5/32 across. Rears were slightly more worn in the center, fronts were even across. This is why we rotate tires.


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## obermd (Mar 3, 2012)

At 4/32" I would be looking to replace my tires in the next month or so. Going into winter people need to remember that you're not dealing with a single surface tension meniscus of water, but two - one on the road and one on the tire. Water sits at 2/32" of an inch deep on almost all surfaces. You need to take into account the water stuck to the tire in the form of slush.

Thanks for tracking this for us.


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## XtremeRevolution (Jan 19, 2012)

I felt that I need to supplement my conclusions in this thread with some more recent revelations. 

1. I was wrong about traction. I fought tooth and nail but ultimately discovered on my own, after some explanations in other threads, that the smaller contact patch at higher pressures results in a tire that breaks loose more easily due to the contact barrier heating up under friction. This was particularly evident in wet conditions. I feel it is valuable for any spectators that reach this thread in the future to know this. 

2. The tread depth on my Eco tires was higher than I had measured. I noted earlier that my measurements changed when I lost my first tread depth gauge, which I blamed on calibration. Turns out, this was user calibration, not equipment calibration. My new tread depth gauge, which is analog, reads in both metric and SAE, and I was recording metric millimeters initially. My tires had more tread depth than expected. That being said, the tread did not solve for the fact that the rubber compound had degraded to the point where wet traction, even at manufacturer recommended pressure, was compromised and no longer felt safe. 

In concluding this stubborn experiment, I would not run my tires at maximum sidewall again unless I found myself with a substantial highway commute. My replacement tires, which are 235/50/17 bridgestone turanza serenity plus, are kept at 38-40 PSI (max sidewall is 51psi).


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## DMC (Oct 22, 2012)

Just a quick comment on this. I've checked in on this thread with interest from time to time. I just purchased a set of winter tires on steel wheels from a forum member, and put them on a couple of weeks ago. Before that I ran the original tires. I got 102,000 miles out of the OEM Goodyears. I will be replacing them in spring when the Eco rims go back on. I have run them as high as 40 psi but backed them down to 35-38 due to our lousy roads here in WI. The slight gain in MPG was not worth the rock-hard ride quality with them higher. I don't have a tread depth gauge but the original tires are at the wear bars. Nothing special done to them, just rotated at every oil change. One finally developed a slow leak the last month or so before I put the winter tires on. I still have them in the garage and can post a pic if anyone is interested.


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