# tire pressure



## audiophile64 (Apr 16, 2011)

I just checked my tire pressure and its only 30 all around when it should be 35 (I have 2011 eco 6 speed)and wondered why my mileage is only gone to 30.3 mpg on DIC with mostly highway miles so far about 1500 total.I am so stupid to not check sooner have hjad the car about 2 months.Is it safe to put the pressure to like 37 lbs all around? Does anyone know what the max pressure is on the sidewall for the stock eco tires ?


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## LucyCruze (Jul 1, 2011)

Personally, I wouldn't go higher than 35psi when you fill up the tires. When you're driving, the air inside the tires heats up and will increase the pressure by a couple psi. If you fill up to 37, you'll be at 39 or 40 when you're driving.


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## NBrehm (Jun 27, 2011)

It's safe to put 37 in, but go with the manufacturers recommendation, someone way smarter than you or me figured out the best tire pressure for this car. Any gain you get in MPG by going above the recommended pressure will be negated by the tire wearing unevenly in the middle and your braking distances will increase, both dry and wet traction will get worse etc etc. 37 won't make a difference either way but I would just go with the correct 35PSI. You should also never EVER drive on a tire inflated to max PSI, it is extremely dangerous. That is there for people mounting the tires to seat the bead.


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## Patman (May 7, 2011)

The lower tire pressure creates more rolling resistance and thus lower mileage. Put it at 35 before drving and your mileage should increase. Don't worry about having too much pressure unless you are around the 60 PSI range.


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## bartonmd (Jun 30, 2011)

LucyCruze said:


> Personally, I wouldn't go higher than 35psi when you fill up the tires. When you're driving, the air inside the tires heats up and will increase the pressure by a couple psi. If you fill up to 37, you'll be at 39 or 40 when you're driving.


The tire pressures on the door are always "cold" pressures... If they tell you 35 PSI cold, they are expecting it to get 10% higher than that when at operating temperature.



NBrehm said:


> It's safe to put 37 in, but go with the manufacturers recommendation, someone way smarter than you or me figured out the best tire pressure for this car. Any gain you get in MPG by going above the recommended pressure will be negated by the tire wearing unevenly in the middle and your braking distances will increase, both dry and wet traction will get worse etc etc. 37 won't make a difference either way but I would just go with the correct 35PSI.* You should also never EVER drive on a tire inflated to max PSI, it is extremely dangerous. That is there for people mounting the tires to seat the bead*.


 
Nope... On a car, go by the door sticker; but max PSI on any tire is for the max specified load rating of that tire... If a tire is rated at 3000#, it is rated at 3000# at its max pressure... This is why the tires say "load capacity 3000 lbs at 80PSI max"... The tire is only rated at, say 2000# at 44PSI... Usually, the rear axle load rating of a single wheel 3/4 or 1-ton truck is based around the tires' load capacity at max sidewall pressure, so they are run at max PSI all the time it's loaded...

There is typically a separate note saying "max pressure to seat bead - ___ PSI"



As a side note, does anybody notice that these energy conserving tires drop pressure really quick? I've got to put about 2PSI a month in the tires on my ECO, vs. 2PSI every 4-5 months on the truck tires on my truck and Trailblazer, as well as the "normal" tires on my Lesabre...

Mike


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## Dale_K (Jul 16, 2011)

Yeah, my car sent me an email telling me the tire pressures were a little low. I checked the DIC occassionally and saw 33 and felt it was OK but then I checked them cold and they were only 31. 

I put 35 in them all and the handling is very much better. I don't know if I'll notice any difference in the mileage but the handling improvement is enough of a reason to air them up.


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## SilverCruzer (Nov 30, 2010)

I inflated my tires to 35 cold, and after driving a bit, they hit 37 to 38. I am wondering if I overfilled them.


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## bartonmd (Jun 30, 2011)

SilverCruzer said:


> I inflated my tires to 35 cold, and after driving a bit, they hit 37 to 38. I am wondering if I overfilled them.


See post #5 in this very thread... The pressure goes up ~10% when the tires get hot... 35 + 3.5 - 38.5... You are fine.

Mike


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## Vetterin (Mar 27, 2011)

I keep mine at 39 psi and no matter when I check my DIC it never varies by more then +/- 1 psi.
FWIW, a underflated tire will build up more heat than a properly/overly inflated tire so don't take that 10% figure to the bank.
If you really want to talk about high tire pressure go visit some of the hypermilers forums.


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## SRT8-to-Eco! (Jul 12, 2011)

41 psi here cold. 

Moves up to 43-45 in the middle of my commute on the freeway on a 90 degree day.

Major improvement in MPG.


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## bartonmd (Jun 30, 2011)

Vetterin said:


> FWIW, a underflated tire will build up more heat than a properly/overly inflated tire so don't take that 10% figure to the bank.
> .


Correct, but that's a rule of thumb... It it usually less than that, but not usually over that, unless you start talking about running on a track or something...

Mike


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## WHITECO (Mar 31, 2011)

I have had mine set at 44psi for the past 4 months...If I was really going to hypermile I would put them upto 51psi which is the max on the sidewall and probably improve my mpg a little more...no issues and better gas mileage too. 35psi would be no problem at all.


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## Quazar (Apr 28, 2011)

WHITECO said:


> I have had mine set at 44psi for the past 4 months...If I was really going to hypermile I would put them upto 51psi which is the max on the sidewall and probably improve my mpg a little more...no issues and better gas mileage too. 35psi would be no problem at all.


I have been at 45 for a few months now. 

The tires are rated at 51 psi and 1433lbs at max psi per tire, or 5732 pounds for the entire car. There is no danger, even with passengers of the tires becoming dangerous by maxing the PSI on this car. The Chevy Volt which is 700 lbs more uses these tires at 35 psi as well.

Every 3.5 psi ~ 1 mpg. 

As far as unever wear, after 12000 miles I have none, I measured it this morning.

The true downside is turning speed is reduced and stopping distance is increased. You should be more careful especially in rain.


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## NBrehm (Jun 27, 2011)

Lol, I'm not gonna argue the point anymore. I just think it is funny most of you will wear a set of tires out faster to save $1.50 a fill up at the pump. Like watching congress make a budget.


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## Vetterin (Mar 27, 2011)

Like I want to keep these tires on my car forever since they are the greatest handling, high performance, all season tire ever produced.
Can't wait for winter with them!


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## LucyCruze (Jul 1, 2011)

Vetterin said:


> Like I want to keep these tires on my car forever since they are the greatest handling, high performance, all season tire ever produced.
> Can't wait for winter with them!


You really can't complain too much about the tires' handling and performance if you've overinflated them. Overinflating reduces handling and performance, so....


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## WHITECO (Mar 31, 2011)

There is no drop in handling or performance with my tires at 44psi...the only thing that has changed is the comfort...That is where the manufactures have us all snowed...They have to make a car comfortable to drive in so they keep the reccomended pressures lower to keep a nice smooth ride...raising the pressure 5-10psi is by no means overinflating a tire. Then to top it all off by driving slow and trying to get good gas mileage you won't be wearing your tires out as fast as you would by accelerating quickly and cornering hard...That's what wears a tire out.

I am willing to bet my tires will last longer then yours inflated at 35psi


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## LucyCruze (Jul 1, 2011)

You can't say it doesn't affect handling or performance. It's common sense. When your tire is inflated past the recommended psi, it bulges out. (It may not be noticeable to the naked eye, but it does... it's designed for 35psi. At any other psi, the tire isn't the shape it's intended to be...)

A bulging tire has less contact with the road -- which is what improves fuel economy -- but it also means less friction against the road when you're trying to stop or make a turn.

From one of the many articles I found on the subject...



> The Michelin engineering team ran a computer simulation on a family car with pressures increased to 44 psi from the proper 35 psi.
> 
> They report, "Increasing inflation pressure can negatively affect performances such as handling, wear life, worn appearance and braking traction. For instance, our modeling simulations predict, with an increase from 35 to 44 psi, up to 6-per-cent degradation in stopping distance can occur on wet/dry surfaces."
> 
> ...


I don't doubt that the manufacturers are concerned with how smooth the ride is (that obviously affects sales...) but I'd have to guess that customer safety is a larger concern and is something that affects sales quite a bit more than comfort level...


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## bartonmd (Jun 30, 2011)

WHITECO said:


> There is no drop in handling or performance with my tires at 44psi...the only thing that has changed is the comfort...That is where the manufactures have us all snowed...They have to make a car comfortable to drive in so they keep the reccomended pressures lower to keep a nice smooth ride...raising the pressure 5-10psi is by no means overinflating a tire. Then to top it all off by driving slow and trying to get good gas mileage you won't be wearing your tires out as fast as you would by accelerating quickly and cornering hard...That's what wears a tire out.
> 
> I am willing to bet my tires will last longer then yours inflated at 35psi


Eh... I've worn the centers of 2 sets of tires by doing this very thing... A tire is set up to have a flat pattern and wear evenly at a certain weight at a certain pressure... If you go above that, they will wear the centers, and handling will degrade... They will wear the outsides if you have the pressure too low, also... The pressure won't always be the same for different tires on the same vehicle, though... I have to run the 10-ply tires on the Trailblazer at 45PSI, whereas the stock 4-ply tires wore well at around 35psi...

Mike


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## NBrehm (Jun 27, 2011)

LucyCruze said:


> You can't say it doesn't affect handling or performance. It's common sense. When your tire is inflated past the recommended psi, it bulges out. (It may not be noticeable to the naked eye, but it does... it's designed for 35psi. At any other psi, the tire isn't the shape it's intended to be...)
> 
> A bulging tire has less contact with the road -- which is what improves fuel economy -- but it also means less friction against the road when you're trying to stop or make a turn.
> 
> ...


I like her.....:signs015:

She is 100% right, that pesky physics gets in the way once again.


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## dacruze (Jul 15, 2011)

Ya'll are hilarious, but i tend to actually agree w/ what all of what ya'll have said. Overinflation causes abnormal wear, more braking distance, but gives you more MPG's. I did front end work for years when i was a mechainc, mounted and balanced 'em too. So each one of us has to make the decision better MPG's of save the life of the tire a little. The question i ask myself is "How can i kill the goodyears soon, and get michelin's, which are certainly the best tires ever produced !!!! The offer a energy saving line too. - Dan


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## scarletwhite (Aug 27, 2011)

dacruze said:


> Ya'll are hilarious, but i tend to actually agree w/ what all of what ya'll have said. Overinflation causes abnormal wear, more braking distance, but gives you more MPG's. I did front end work for years when i was a mechainc, mounted and balanced 'em too. So each one of us has to make the decision better MPG's of save the life of the tire a little. The question i ask myself is "How can i kill the goodyears soon, and get michelin's, which are certainly the best tires ever produced !!!! The offer a energy saving line too. - Dan


I can't help it. I'm a Michelin snob. I took them for granted on my last 2 cars, then replaced my factory Michelins at around 80,000 miles with Yokohamas (which were not cheap!). My TSX never rode the same after that. I will never stray from Michelins again and they were a big selling feature for me on the LTZ.


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## NBrehm (Jun 27, 2011)

Lol, while the goodyears are worse Michelin's are by no means the best tires around either. However they do have a distinctive ride quality that seems to be unique to them. But hey if you want to get rid of the tires then you are on the right track. Spend $500.00 to save $50.00


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## WHITECO (Mar 31, 2011)

Here is an interesting link....this will get you started on inflation and the do's and dont's

hyper inflation: let's cut to the chase - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com


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## LucyCruze (Jul 1, 2011)

Eh... random people posting stuff on a forum isnt the best source to back up an argument... after skimming through some junk, I did find some actual links to potentially helpful info, but I'll read them tomorrow. (It's late and I'm tired... haha.)

Regardless, I dont know why people hold any online articles, no matter how scientific sounding, in such high regard. The bottom line is... the people who are engineering and producing your tires know them much better than any schmuck with access to some crappy WordPress templates and a domain name does. If the engineers say that 35 psi is what's best, then I've gotta trust them. Maybe I'm naive, but until I've earned an engineering degree and designed, tested, etc. a similar tire, I'm not gonna pretend I'm smarter than them. 

I laugh when I see people post up stuff about tearing out their Eco shutters because "the GM engineers are total morons" but I really cant chuckle at threads like this. No one will die from screwing around with their grille... but if I, or a friend or family member, gets rear-ended by some tool who couldnt stop in time because he overinflated his tires to save a buck at the pump... I'm gonna be pretty dang unhappy.

Don't screw around with things that directly affect your safety -- follow the instructions.


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## NBrehm (Jun 27, 2011)

WHITECO said:


> \
> 
> hyper inflation: let's cut to the chase - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com


Not to be the jerk again but that is some of the best ignorance I've seen yet. That is an article of pure opinion based on nothing. Having sold tires for the last few years at the shop and talked with reps and engineers from bridgestone, goodyear, Nitto and michelin almost ALL of what he has written is flat out wrong and some of it is dangerous. At best you are looking at 2MPG by inflating your tires to max. I know someone will say " I got 15MPG better" but let's be realistic, no you didn't. Just like a couple bolt ons isn't going to propel your little Cruze to mid 14's, inflating your tires like a balloon isn't going to get you 5 MPG. I don't hypermile, or draft trucks, or pump my tires up to 60PSI and I am still averaging a combined MPG of almost 42, and it has mostly been in the city in the heat. You will gain more by learning how to manage your momentum than any of these ridiculous Urban Legends

Edit: I have friend at Nitto who is one of the tire engineers, I'm going to shoot him this thread in an E-mail and see what he says to put this to bed once and for all.


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## WHITECO (Mar 31, 2011)

In this instance I thought it might be best to pursue this issue a little further. I have come to realize sometimes what we are told is definitely not in our best interest, but in the best interest of the company. Tire manufactures want to sell tires, I get that and I am all for companies making money.

What sometimes we believe is the truth isn't necessarily the case. I am starting to believe that you can make a tire last longer and get better mpg while doing it by having it inflated higher then the recommended pressure on the vehicle. 

Everyone can take this for what it's worth; it probably won't change anyone's mind on how they feel about this issue. But, I called Goodyear Customer service 1-800-387-3288 and told them I had the assurance fuel max tire and that the dealership had put them to 44psi but my car said it should be 35psi. The rep said "what does the side of the tire say?" I said "51psi"

He then said "It should be no problem; it's not the original tire on the car right?"

I lied and said "It wasn't".

p.s. I felt bad about not saying it was the original tire on the car, so I called back with the premise of saying I had a Cruze and to make sure there was no issue with safety.

I got a different person on the phone and she said "No safety issue to run 44psi, No issue with warranty, no excess treadwear"

I said, "Thank you for saying all that cause I was nervous to have 44psi and the side of the car says 35psi but I was getting better mpg" and she said and I quote, "YES YOU WOULD"

So what I take from this is 2 things, the recommended pressure for the car with original tires is set for the car, in this case 35psi.

The manufacturer has no problem with the tire being run at 51psi he/she said 44psi would be fine.

From those 2 things I feel totally comfortable with running 9psi more then the recommended pressure for my car, but 9psi less the max psi recommended by the manufacturer.

You are all free to do what you choose.


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## bartonmd (Jun 30, 2011)

WHITECO said:


> In this instance I thought it might be best to pursue this issue a little further. I have come to realize sometimes what we are told is definitely not in our best interest, but in the best interest of the company. Tire manufactures want to sell tires, I get that and I am all for companies making money.
> 
> What sometimes we believe is the truth isn't necessarily the case. I am starting to believe that you can make a tire last longer and get better mpg while doing it by having it inflated higher then the recommended pressure on the vehicle.
> 
> ...


So you told him what vehicle it was, and he looked up the weights front and rear, and did the calculation (or looked it up in their computer, if it was a stock size) and told you what the optimum pressure was for those tires on that vehicle??

I had been running the 10-ply slightly oversized BFG ATs on my TB at 37PSI and they were wearing on the sides, so I called BFG, and they calculated that that tire on that vehicle needed like 45 in the front and 55 in the rear, based on the factory pressures with the factory size/type of tire... Been wearing great now!

I ran the factory tires at 37-39PSI and the middle ended up wearing out of them (the middle was ~3/32 lower than the sides when I replaced them)... Did the same thing with my Caprice, and it did the same thing... 5PSI over the door (with factory size/type of tire), and the tires got really worn out in the middle...

If you didn't do this, I am guessing that they were just telling you that the tire wouldn't explode if you ran it at 44PSI, when the sidewall max is 51...

Mike


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## sciphi (Aug 26, 2011)

Just don't exceed the max sidewall. That's worked for me for forever, and I'm sticking to it.


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## LucyCruze (Jul 1, 2011)

*sigh* I'm really sorry to be beating a dead horse, but I really feel this is a serious safety issue... let's talk high school physics one more time and then I promise not to gripe about it anymore, okay?

TIRE WEAR

When your tire is overinflated, less of it is touching the road. That means that the weight of your car is now supported by a smaller area, which increases the stress (load divided by unit area) on that part of your tire.

More stress on that area of the tire means it's being pressed harder into the pavement... which means as it's digging into the road to propel your car, it's going to wear down more quickly.

STOPPING DISTANCE

Newton's First Law of Motion -- it basically says that you're gonna need an opposing force to halt your vehicle's motion... and that force happens to be friction.

Underinflated tires are, in a way, "softer" and deform against the road more, which creates more friction and is why MPG is reduced. Overinflated tires are "harder" and cause less friction, which is why MPG is increased. However, a tire that creates less friction while driving also creates less friction while stopping. By inflating your tires past the recommended PSI, you are sacrificing stopping distance.

So...

You're right about overinflation improving fuel economy slightly, but you're wrong about your tires not wearing out. It's not an opinion -- it's a fact. Anyone with a basic understanding of physics can see that. In addition to wearing your tires out, you're putting yourself and other drivers at greater risk of being in an accident. I'm not saying you're gonna have a blow-out or anything -- not at 44psi anyway -- but there might come a day where you wish you could have stopped a couple feet sooner.

I'm really not trying to be a jerk to you or anything. I just think it's important to fully understand the reality. If you still want to take the risk, then there's nothing else I can do about that, but at least then you'd be aware of it. Good luck, thanks for reading my rambling posts, and seriously, be safe out there.


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## Vetterin (Mar 27, 2011)

LucyCruze said:


> *sigh* I'm really sorry to be beating a dead horse, but I really feel this is a serious safety issue... let's talk high school physics one more time and then I promise not to gripe about it anymore, okay?
> 
> TIRE WEAR
> 
> ...


Well, you have a good, long, prosperous life! As for me, I'm keeping my tires at 39 psi and putting my life in the hands of the tire Gods. On a side thought, wouldn't overinflated bald tires get even better mileage? 
Long live physics!


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## Boost (Aug 13, 2011)

Great informative thread! I see that generally Cruze owners are pretty educated and intelligent, that's awesome. There are no tire gods  only One GOD...


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## dacruze (Jul 15, 2011)

Great informative thread! I see that generally Cruze owners are pretty educated and intelligent, that's awesome. There are no tire gods  only One GOD...[/QUOTE]


:sigh:Only one God and One Way, Jesus!!

By the way, Fred Flinstone didn't have to worry about pressures or stopping distance, he used his feet.

Seriously though, I guess everyone has to do what they think is best for them, just be safe!!!- Dan


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## Boost (Aug 13, 2011)

yes sir  And tires are the most important part on any car, the only one that touches the road! I would not stray too far from the recommendation of both the tire and vehicle manufacturers. When in doubt, read the Owner's Manual...


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## NBrehm (Jun 27, 2011)

From Rob at Nitto Tire

"Hi Nick, 
I read through the thread on the forum you asked me to and would like to clear a few things up for the folks involved. The manufacturers recommended tire pressure is based on many factors, first and foremost is the weight on the tire itself. To an extent all parties involved have some basis of being correct. Having said that I would like to add some cold hard facts about tire inflation. Increasing and decreasing the PSI on any tire has positive and negative effects, a few PSI here or there will not make much of a difference but too much or too little can have negative affects and even become dangerous. Underinflation will make a car handle better (to an extent) and overinflation will make a car get better mileage (again to an extent). Sicne we are discussing adding PSI I will just leave you with this. While increasing PSI will gain gas mileage there is very minimal gain, 1-2% per 10 PSI over recommended pressure is what we found to be a good average. Or realistically for most cars about 1-2 dollars a tank. On the flip side there is an average increase of 15-30% in tire wear on the center of the tire, so for saving money you can expect to but a new set of tires about 15-30% sooner than running at proper PSI. Long run you will lose money and by quite a bit. Also on average for every 5PSI we increased most of our tires inflaton weight we saw 10-20 feet extra braking distance (roughly a car length) on our test vehicles and a degradation in handling performance which varied acrossed the entire spectrum of our lineup, although not consistent every tire did poorer in handling at higher PSI. And of course the other major factor is sidewall impact, a tire at/near it's max inflation weight is more then 75% more likely to fail ar the sidewall with an impact VS a properly inflated tire. There are exceptions to every rule and personal preference in ride and handling can be safely adjusted with minor pressure changes (we recommend no more than 5 PSI either way from Man. Specs) you should really avoid increasing pressure with the exception of carrying extra weight, something like a trailer per say. I hope some of this info helps out."


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## bartonmd (Jun 30, 2011)

Thank you, Nick and Rob at Nitto!

Mike


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## Boost (Aug 13, 2011)

bartonmd said:


> Thank you, Nick and Rob at Nitto!
> 
> Mike


+1

:goodjob:


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## NBrehm (Jun 27, 2011)

Vetterin said:


> On a side thought, wouldn't overinflated bald tires get even better mileage?
> Long live physics!


ummm, no. If Isaac Newton was alive he would commit suicide reading this thread :goodjob:


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## Boost (Aug 13, 2011)

I'm pushing it (but this is true!) Suicide would have been against the religious beliefs of Sir Isaac Newton. I had to, back on topic!!


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## NBrehm (Jun 27, 2011)

Boost said:


> I'm pushing it (but this is true!) Suicide would have been against the religious beliefs of Sir Isaac Newton. I had to, back on topic!!


Lol


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## toxaris (Mar 19, 2011)

*Under inflation for winter?*



NBrehm said:


> From Rob at Nitto Tire
> 
> "Hi Nick,
> Increasing and decreasing the PSI on any tire has positive and negative effects, a few PSI here or there will not make much of a difference but too much or too little can have negative affects and even become dangerous. Underinflation will make a car handle better (to an extent) and overinflation will make a car get better mileage (again to an extent). "


What could be the downside of under inflation? The recommend pressure for my Cruze is 35 psi, however I went to the dealer today for an oil change and they set the pressure to 30. When I asked about this the service guy said it was a good idea for the winter and I can revert to 35 in the spring. Does under inflation give better traction in cold weather or on snow and ice?


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## NBrehm (Jun 27, 2011)

Under inflation will give you more surface area yes, and could give you better handling on dry roads if you don't drop too much pressure. It will make the car worse in snow (you want the contact area smaller so you cut through the snow and don't slide on top of it). Under inflation will cause the outside edges of the tire to wear faster than the center. It will also make the car sloppier if you go too low as it will actual do the same as giving you softer springs and the car will roll more in corners. Again, best bet is go with manufacturers specs. One last thing to keep in mind is if they put in 30PSI on a 60 degree shop, when temps get to freezing you are looking at about 25-26 PSI. If anything they should have been going to say, 38PSI in the shop and when you get out in the cooler air it will drop to the recommended 35PSI.

I can't think of a single worthwhile reason to lower tire PSI for the winter.


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## toxaris (Mar 19, 2011)

I completely agree. I also read that many experts agree that it is better to have the tires over inflated than to have them running under inflated. Not only that the fuel consumption will increase but it could be a safety issue. Thank you for your answer.


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## Dale_K (Jul 16, 2011)

I'd say the car will have more traction at 30 psi but it will handle worse because the tires will kind of roll over on the sidewall when you go around a corner.


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## sedanman (Dec 10, 2010)

All I know is when you do get around to filling your tires you'd better use nitrogen and not that crap air you're breathing with is mostly nitroge...what was I saying again? I'm cornfused...


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## SkullCruzeRS (Nov 3, 2011)

Okay so here is my question. My 1LT came with 16 inch alloys door sticker says 35psi. I have since upgraded to 18 inch tires and I've read in some posts owners with 2LT's or the LTZ's they say their sticker says 30psi. I'm sure theirs has the sport suspension which may make some difference. Should I run with 35psi or 30psi? I currently have them at the recommended 35psi.


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## bartonmd (Jun 30, 2011)

toxaris said:


> What could be the downside of under inflation? The recommend pressure for my Cruze is 35 psi, however I went to the dealer today for an oil change and they set the pressure to 30. When I asked about this the service guy said it was a good idea for the winter and I can revert to 35 in the spring. Does under inflation give better traction in cold weather or on snow and ice?





NBrehm said:


> Under inflation will give you more surface area yes, and could give you better handling on dry roads if you don't drop too much pressure. It will make the car worse in snow (you want the contact area smaller so you cut through the snow and don't slide on top of it). Under inflation will cause the outside edges of the tire to wear faster than the center. It will also make the car sloppier if you go too low as it will actual do the same as giving you softer springs and the car will roll more in corners. Again, best bet is go with manufacturers specs. One last thing to keep in mind is if they put in 30PSI on a 60 degree shop, when temps get to freezing you are looking at about 25-26 PSI. If anything they should have been going to say, 38PSI in the shop and when you get out in the cooler air it will drop to the recommended 35PSI.
> 
> I can't think of a single worthwhile reason to lower tire PSI for the winter.


Actually, in the winter, you're fighting a battle between getting ground pressure up (less tire on the ground) and getting biting edges on the surface... Typically, a tire with a little more pressure will grip on snow/ice better than one with a little less pressure... This is one of the reason snow tires say to inflate them ~2PSI higher than the door sticker...

Mike


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## minsik (Oct 24, 2013)

New Aussie Cruze owner and so learning heaps. SRi-V sedan with Bridgestone RE050A tyres. 
Plate on the door sill says 36psi. Dealer supplied the vechicle with tyre pressures at 47/49/50/47 PSI and the spare at 44PSI (book says 60PSI)

Pressure measure with a digital tyre pressure gauge simple but solid made Jaycar unit, brand new.
Digital Tyre Pressure Gauge - Jaycar Electronics which is supposed to be within .5PSI. 


So the gauge could be faulty or poor reading? but then something is not right somewhere! 
The ride is firm (but its supposed to be the Aussie tuned suspension) and I did not think it was overly firm. 
Certanly the handling is like glue to the road but while 40 sounds like a reasonable stretch nearly 50 seems a little too high. What do you think?

I forogt to add 300KM only so far.

Minsik


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## obermd (Mar 3, 2012)

According to Firestone, one of the main contributing factors in the Ford Explorer Rollovers was tires failing because they were under inflated. Under inflated tires are at high risk of sidewall failure. Never inflate the tires to below the door placard and then drive on them. Get a good tire gauge and use it. The TPMS can be fooled.


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## mc2crazy (Oct 25, 2013)

obermd said:


> According to Firestone, one of the main contributing factors in the Ford Explorer Rollovers was tires failing because they were under inflated. Under inflated tires are at high risk of sidewall failure. Never inflate the tires to below the door placard and then drive on them. Get a good tire gauge and use it. The TPMS can be fooled.


I'm glad someone had the sense to post about using a good tire gauge!

I'm a new Cruze owner so the pros and cons in this thread were interesting. I haven't checked the tire pressure yet, but expect the dealer will have about a 2psi difference between tires which is not noticeable. I'll stick with the recommended pressure which does change with the ambient outside temperature. Our cars are kept inside a basement garage so that should be within the allowance in our temperate climate here in GA.

I use 2 digital tire gauges and occasionally verify that they read the same. They work great from the low psi in my ATV to the high pressures in my truck and trailer tires.

BTW, When I lived in the snow belt south of Buffalo, NY I ran the tires softer in the winter because most of the traction on slippery roads is on the edge of the tire's tread in those conditions. I'm glad I don't have to deal with that mess anymore!


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## nds76 (Aug 14, 2016)

I only read a couple of pages of this thread. What I want to know is should I use the psi recommendation on the door or whats on the tire itself? Right now they are all at 32-33 psi.


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## jmurtari (May 13, 2013)

Folks,

I've got a 2013 ECO/MT, currently 52,000 miles on the original tires. For most of the year I've cold inflated them to 45 PSI (the spec cold inflation limit is 50). In the winter I do drop them for traction purposes. I've rotated them according to spec. The tires are Goodyear Assurance M+S, 215/55R17, Tread wear 580, Traction A, Temp A.

The wear across the tires looks pretty even and they still have some tread life. Definitely helped mileage. I've noticed you do need a little caution with the MT. In neutral the car will start to roll on even a slight incline.

Definitely better mileage.
Hope this helps!
John


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## 91794 (Mar 25, 2015)

underinflation dissolves and overheats the tire sidewall from the inside out and is visible as rubber dust when the tire is dismounted. don't do it. 

37 PSI is fine. so is 40 PSI especially if it's 20F and subzero weather is expected. 

Yall overinflators and underinflators are misguided and are hazardous to all us proper-tire-inflating drivers, because it's us you are going to crash into some day. 

Please consider to properly inflate your tires, PEOPLE !

51 PSI is hazardous if you ever decide to turn or stop suddenly, or if you hit a rock/road-hazard (POP goes the tire.) 

45 cold pressure is also asking for increased stopping distances on all road surfaces and reduced lateral grip on all road surfaces. but might be better if you are drifting the car around a dirt track maybe in a demolition derby. good luck.


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## MRO1791 (Sep 2, 2016)

Ahh, the seemingly never ending tire pressure debate rages on. There are strong opinions on this that are based more on emotion than facts.. but feel free to do as you will.. but let me break down a few facts, and I've had this discussion and debate on other forums, and done quite a bit of research, but don't take my word for it, verify if you have any doubts.. 

Myth: Using the Tire side wall pressure will cause accelerated center tread wear.
Fact: Only pressures well ABOVE the tire's rating will cause center wear, and WELL above because you need to be stretching those STEEL belts in the radial tire to get the center bulge. 

Myth: Using the Tire sidewall pressure will make you tires more likely to get a flat. 
Fact: The tire manufacture tested the tire at the sidewall pressure (cold psi) and at full rated load for the tire, it is no more likely to get a flat at that pressure than a lower pressure. 

Myth: The OEM pressure is very precisely calculated for the CAR, and thus any tire on that car
Fact: The OEM will specify a pressure lower than the maximum on the tire sidewall, because it offers a better ride quality, AND because the car will not be using the maximum load capability of that tire. But, if you load your car beyond or in some cases at it's rated load, your tire may well become under inflated at the higher load. 

Myth: Tires at the Tire side wall pressure will have less traction than the lower door sticker pressure
Fact: The only type of condition where lower pressure aids traction by a significant amount is in loose sand, and that is well below the normal pressure range, and more an off-road trick at low speeds. A fully inflated tire per the tire manufacture rated pressure will have just as much traction as one rated per the door sticker, traction is based on friction, a larger contact patch at a lower pressure will have a lower effective pressure on a larger area of contact, but the friction is a function of the overall force, and coefficients on tire and surface. The overall force between the 2 is the same, as is the coefficient of friction, thus there is no reason under normal road conditions to expect less traction for a fully inflated tire, and it will perform better in some conditions such as snow, slush, and puddles than a less inflated tire, since it will better resist hydro-planing and the higher contact pressure over that small contact area improve traction in those conditions. 

So, right now you might be wondering.. why does the car OEM recommend a lower pressure if the tire rated pressure is better in nearly any condition? 

That is a good question, and there is a very simple answer: Ride quality. OEMs are in the business to sell cars. A lower pressure will smooth out the ride, offer a bit less stress to the suspension, as the tire absorbs a bit more energy at a lower pressure. 

The car OEM pressure is safe, it won't hurt anything, and will provide a smoother ride.. but the tire rated pressure will also be safe, won't hurt anything (if the car needs a tire cushion for the suspension, the car OEM is dangerously negligent), it will be a bit less smooth.. but offer better MPG, and prolong the life of the tire.. yes, the tire will last longer with the tire rated pressure than the lower pressure. The less flex of the tire, the less heat it generates, and it is heat that is the enemy of tires, and the speed ratings are due the ability of a tire to deal with heat. 

So, in conclusion, pick what you prefer, but don't be concerned about any pressure between the OEM door sticker, and the tire sidewall rated pressure. For me I always go with the tire rated pressure, and in many, many miles never had any unusual wear, nor problems.. and some tires I had went by age long before they did by wear. (7 years is about it, since the rubber hardens).


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## Jacque8080 (Oct 31, 2017)

I have over 200,000 miles at 60 psi hot on a Cobalt SS/SC. Even tire wear. Bone shaking ride.

More miles on other vehicles with similar results.

It increased the hwy mileage about 5 mpg by reducing the contact patch. Any concerns I have about reduced handling were nullified at track days. Braking wasn't reduced because the weight transfer increased the contact patch. Acceleration was reduced in 1st gear. Lateral acceleration increased. This was further aided by toe out and increased negative camber.

I recommend avoiding all of the above. It was all done to change specific handling characteristics.

Most people are on the level that they don't notice their tire is low on pressure, have directional tread facing the wrong way, have summer tires on in the cold, mismatched tread, or blown suspension dampers. This should be level 1. Focusing on driving when driving should be level 0.


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## stanman13 (Aug 2, 2016)

MRO1791 said:


> Ahh, the seemingly never ending tire pressure debate rages on. There are strong opinions on this that are based more on emotion than facts.. but feel free to do as you will.. but let me break down a few facts, and I've had this discussion and debate on other forums, and done quite a bit of research, but don't take my word for it, verify if you have any doubts..
> 
> (edited for brevity)


Excellent breakdown here. The only thing I would add is that the tire manufacturer tested the tire at pressures at least 50% higher than the rated pressure, possibly more. That's the nature of pressure testing. Also, note that the sidewall pressure ratings are maximum _cold_ pressure. The manufacturer has accounted for the very slight increase in pressure that occurs when the tire warms up.

For both my vehicles (2014 Cruze and 2010 Town and Country), I've found that 40psi seems to be the sweet spot for my preferences. Both have 16" wheels. When I was younger and had more time for such things, I would test the tires front and rear on the vehicle with chalk marks and a flat parking lot to find the ideal pressure, but that's really overdoing it for a daily driver.


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