# 45PSI tire pressure



## Ger8mm (Mar 13, 2014)

I have been reading about hyper-milling and they are putting MAX PSI in the tires. I thought it was really bad to do this, considering if you hit a nice pot hole and given we don't have a spare lol. Any thoughts about this?


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## XtremeRevolution (Jan 19, 2012)

I have no reason to believe that inflating tires to max sidewall increases the risk of blowout in a pothole. Sure, the stiffer wall arguably will not conform to the structure of the pothole as well and may burst as a result, but it will be a rare occasion that you would hit a pothole and have a blowout at max sidewall and not have a blowout or bend the rim at GM's suggested pressure. In my mind, the rim is more expensive to replace than the tire, especially with the Eco and LTZ trims. My realtor was coming back with us from showing a house and hit a pothole in his BMW. Tires were at recommended pressure and he bent both rims. Think about just how hard you have to hit a pothole to blow our a tire. 

It won't be the pressure that blows the tire, but the puncture. 

I've driven 30k miles at max sidewall so far.

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## sx sonic (Nov 25, 2013)

I've probably put 100k miles on vehicles with tires at max sidewall pressure or even a little over without issue. Usually even get above average tire life even with regular aggressive cornering and non frequent tire rotations.

Can't say the same for people that don't stay on top of tire pressure and let it drop much below 30psi. Most of the cars I've worked on that had blow outs had under inflated tires on the remaining wheels.


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## XtremeRevolution (Jan 19, 2012)

sx sonic said:


> I've probably put 100k miles on vehicles with tires at max sidewall pressure or even a little over without issue. Usually even get above average tire life even with regular aggressive cornering and non frequent tire rotations.
> 
> Can't say the same for people that don't stay on top of tire pressure and let it drop much below 30psi. Most of the cars I've worked on that had blow outs had under inflated tires on the remaining wheels.


Under inflation causes excessive sidewall flex and rolling resistance, which generates heat and causes accelerated rubber compound degradation. Max sidewall pressures slow the chemical clock of that rubber compound, making them more malleable under uneven surfaces and improving traction as well.

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## Danny5 (Dec 22, 2011)

The tires on your CTD have a max pressure of 51psi. I keep mine at 42, I don't think either of us would have to worry...


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## Psychomidgit (Jun 9, 2013)

I usually keep mine at 35/36. I've never had an issue with a blow out.


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## Aussie (Sep 16, 2012)

I have always been led to believe that under inflation is more dangerous than over inflation as under inflated tyres build up too much heat.


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## brian v (Dec 25, 2011)

The U.S. Federal Government Mandated TPMS Because of Underinflated TYRES . Thanks to Ford and Firestone and some Goofie SUV Owners !!!!!!!


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## Aussie (Sep 16, 2012)

brian v said:


> The U.S. Federal Government Mandated TPMS Because of Underinflated TYRES . Thanks to Ford and Firestone and some Goofie SUV Owners !!!!!!!


You have just explained why we don't have them on Aussie cruzes no government interference, so far anyway.


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## money_man (Feb 25, 2014)

brian v said:


> The U.S. Federal Government Mandated TPMS Because of Underinflated TYRES . Thanks to Ford and Firestone and some Goofie SUV Owners !!!!!!!


Not Ford's fault Firestone/bridgestone couldn't make a quality tire to save their lives


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## Ger8mm (Mar 13, 2014)

Ok, Thanks for the input, I will try it out and ease my way close to MAX lol


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## obermd (Mar 3, 2012)

Ger8mm said:


> Ok, Thanks for the input, I will try it out and ease my way close to MAX lol


I bumped my Goodyears to 45 PSI for a while and then bumped them to 48-50 PSI. It does take some time to get used to the driving dynamics of the higher pressures.


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## Vetterin (Mar 27, 2011)

While I've never had my Goodyears under 38 psi, I also have never gone over 45 psi. While my mileage might suffer a tad, my sweet spot (for mileage AND comfort) seems to be right between 40-42 psi.


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## money_man (Feb 25, 2014)

The max sidewall pressure assumes cold air as well. So pumping in 51psi cold is fine even with expansion. I'm bumping mine up to 50 for this weekends 3.5hr journey.


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## Aussie (Sep 16, 2012)

I always pump my tyres up when cold and at night. Pumping up on a hot day can give different pressure on the sunny side of the car compared to the shady side.


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## sx sonic (Nov 25, 2013)

money_man said:


> Not Ford's fault Firestone/bridgestone couldn't make a quality tire to save their lives


But didn't the Firestones made to Ford's specifications and installed as O.E.M. tires have exponentially more blowouts than any other bridgestone/Firestone?

Also didn't Ford specify a 27 or 28 psi recommended pressure?


I'd only done limited research on it years ago so I can't recall if that's true. If it is, well then it's Ford's fault and more proof that low tire pressure should be avoided (for readers that aren't already in the know.)


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## XtremeRevolution (Jan 19, 2012)

sx sonic said:


> But didn't the Firestones made to Ford's specifications and installed as O.E.M. tires have exponentially more blowouts than any other bridgestone/Firestone?
> 
> Also didn't Ford specify a 27 or 28 psi recommended pressure?
> 
> ...


You are absolutely correct. The issue with the Exploders was that Ford set the tire pressure too low. Not at all Firestone's fault. 

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## money_man (Feb 25, 2014)

I'll go 50/50 ford and Firestone at fault


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## obermd (Mar 3, 2012)

Firestone did find a problem with the tire that would only occur under overloading conditions, such as the excessively low door placard PSI for the Ford Explorer. This flaw led to more low pressure blowouts than normal for an under-inflated tire.


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## brian v (Dec 25, 2011)

When I am right I am right .. History Boys is and shall remain my subject to Dazzle the Novice with Me Brilliance ! Now Quantum Mechanics is a study that continues to amaze even the brightest minds amongst us . So 45 psi is a safe bet to drive .


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## money_man (Feb 25, 2014)

I worked for bridgestone. On 2500hd and bigger pick ups they like 50psi front and 80psi rear. The tires had a max sidewall of 80psi, those trucks drove until the tires were worn out and never had problems. Max tire pressure on the sidewall is the max you can put in and still drive safety, plain as that. I've seated beads on 44psi max tires by putting 80-90psi into them, they made an insane snap when they went into place but never blew out.


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## Psychomidgit (Jun 9, 2013)

There's a little issue with the thought process though. I know there will be people who will argue that they've had no issues and that it's perfectly safe. From what I've learned, the pressure on the side of the tire is the safe max pressure that the tire should be inflated to at any point in time with a load on it (even when warmed up). Besides that, it causes improper tire wear.

The other thing is that when the vehicle was designed, the tires are accounted for as part of the suspension system. They are the first defense against road shock. Hense why the manufacturer recommends them at a certain pressure. The tires being at that pressure absorbs the road shock well enough to allow the suspension to absorb the rest and to not take as much road shock as it would, helping the reliability of the components such as the shocks, bushings, and bearings. If you continually over-inflate the tires you reduce their ability to absorb that road shock and it ends up transferring that to the components and over time you will wear them out faster. Personally I've kept my tires at the right levels and never had issues as stated before.


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## marden64 (Dec 1, 2013)

Wouldn't keeping your tire overinflated cause abnormal tire wear over time?? Instead of getting 80K out of them, you would only get 50K and end up spending money on tires when you really don't have to.


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## money_man (Feb 25, 2014)

That is a possibility but there are guys on here saying they have lots of miles with pressure bumped up and no uneven wear


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## obermd (Mar 3, 2012)

marden64 said:


> Wouldn't keeping your tire overinflated cause abnormal tire wear over time?? Instead of getting 80K out of them, you would only get 50K and end up spending money on tires when you really don't have to.


Radial tire construction pretty much prevents bulging. Bias Ply and older tire technologies definitely bulged. Assuming your tires aren't under inflated, rear tires tend to wear faster in the middle of the tread and front tires on the shoulders. This is why you rotate your tires.

As a general rule of thumb American car manufacturers set their recommended tire pressures based on ride softness and not on tire performance. Increasing pressure in the tire stiffens the sidewall, which results in a more consistent and predictable tire performance, but at the cost of feeling more road bumps.


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## XtremeRevolution (Jan 19, 2012)

Psychomidgit said:


> There's a little issue with the thought process though. I know there will be people who will argue that they've had no issues and that it's perfectly safe. From what I've learned, the pressure on the side of the tire is the safe max pressure that the tire should be inflated to at any point in time with a load on it (even when warmed up). Besides that, it causes improper tire wear.
> 
> The other thing is that when the vehicle was designed, the tires are accounted for as part of the suspension system. They are the first defense against road shock. Hense why the manufacturer recommends them at a certain pressure. The tires being at that pressure absorbs the road shock well enough to allow the suspension to absorb the rest and to not take as much road shock as it would, helping the reliability of the components such as the shocks, bushings, and bearings. If you continually over-inflate the tires you reduce their ability to absorb that road shock and it ends up transferring that to the components and over time you will wear them out faster. Personally I've kept my tires at the right levels and never had issues as stated before.


I have 30k miles of driving at 51psi and measured tread depth every 3500 miles on rotations and they have work evenly. Not a single anomaly. 

The tire pressure is as a fact not what you think. Tire pressure is inflated cold, during the coldest day of the season. Tires will not burst from pressure until you exceed 200psi. 

I've talked to people on ecomodder and none have noted accelerated wear on any suspension components due to max sidewall pressures. Some of those tin even higher than max sidewall, which in don't recommend. It is the small bumps that you feel more. If GM was so concerned about tire pressure affecting component reliability, they wouldn't have made an LTZ trim with heavy 18" rims and very stiff and thin sidewalls. You never hear people recommending against going from 16" to 18" rims due to suspension component longevity, but I can bet you there is less stress in your vehicle's suspension parts with the Cruze 1LT, 2LT, or ECO wheels at max sidewall than there is in the LTZ at manufacturer recommended pressures. 

This is not a recommendation for all people. The purpose is for improving fuel economy and to some extent ride stability. The Eco feels way too...mushy with manufacturer recommended pressures. I would run those tires at no less than 40psi.

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## XtremeRevolution (Jan 19, 2012)

marden64 said:


> Wouldn't keeping your tire overinflated cause abnormal tire wear over time?? Instead of getting 80K out of them, you would only get 50K and end up spending money on tires when you really don't have to.


It is actually the other way around for two reasons. 

1. The reduced rolling resistance heats up the tires less, which slows the rate of tread compound degradation. 
2. The reduced rolling resistance and smaller contact patch reduces tire wear rate, albeit by a very small amount. As I noted in my previous post, I have 30k miles on my tires at 51psi, measuring their depth with a 1/64" accurate depth gauge and rotating every 3500 miles. Wear is still entirely flat.

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## money_man (Feb 25, 2014)

My diesel asks for 38psi on the door jamb. Is that the same for most cruze's?


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## XtremeRevolution (Jan 19, 2012)

money_man said:


> My diesel asks for 38psi on the door jamb. Is that the same for most cruze's?


Nope. Mine specifies 35 psi.

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## obermd (Mar 3, 2012)

35 PSI on the CDT would probably be under-inflating the Goodyear Assurance FuelMax tires. It's 600 lbs heavier than the ECO MT which XR and I drive. Once again, the door placard inflation pressure is set for ride comfort and not vehicle performance.


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## Aussie (Sep 16, 2012)

Over inflation used to be a problem in the old cross ply tyres but I haven't used these since the 1960's. Can you imagine a car today with 13 X 4.5 inch rims, oh wait someone invented the space saver spare didn't they?


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## obermd (Mar 3, 2012)

Aussie said:


> Over inflation used to be a problem in the old cross ply tyres but I haven't used these since the 1960's. Can you imagine a car today with 13 X 4.5 inch rims, oh wait someone invented the space saver spare didn't they?


You haven't looked closely at a Prius then. I think the Prius uses four space saver spares for normal driving.


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## Psychomidgit (Jun 9, 2013)

Unless the Cruze is built differently than other vehicles it will over time. And yes they account for ride quality but that is not the only reason why they have recommended tire pressures. It's also because tires are an important part of your suspension that take in quite a bit of road shock to protect the other components. By overinflating your tires you are reducing this property, therefore putting more stress on your suspension which overall will reduce it's lifespan. As for LTZ's, it's been accounted for and they've obviously researched how it affects the suspension on that model and figured that it will hold up under normal driving conditions, but, the suspension will wear more quickly than the other models.

Where was this tested? I've seen plenty of tires blow out due to load and also not at 200psi. I will not argue that it is more common that blowouts are due to under-inflation, over-inflation has been a cause also. Over-inflation raises the possibility of puncturing, separating plys, and bubbles in the sidewall. It also increases heat expansion due to the higher pressure the tire will be under when warmed up.


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## obermd (Mar 3, 2012)

I have to disagree about the heat expansion. Using the TPMS in my ECO MT I discovered that if I start at 50 PSI my tires only go up to 52-53 PSI, a 5% increase in pressure. Starting at 45 PSI they would climb to 51-52 PSI, a 10-11% increase in pressure. Both of these were noted on days with the same high temperature just below 100F. The difference can only be from the extra sidewall flex at 45 PSI and was NOT something I would have expected.

Is there a shortened suspension life, probably, but I drove two Pontiac Mini-Vans for 180,000+ miles and never changed the shocks or any suspension parts due to wear. I even asked my dealership about this and they said other than an accident the suspension on those vans was probably good for twice that distance. I see no reason for the Cruze's suspension to be the same way.


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## Aussie (Sep 16, 2012)

obermd said:


> You haven't looked closely at a Prius then. I think the Prius uses four space saver spares for normal driving.


Hybrid cars are town queens that can use the highway when necessary so as I would never be interested in one I don't consider them in my list of cars I am likely to ever want.


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## obermd (Mar 3, 2012)

Aussie,

If you get a chance, test drive a Volt or Ampera (Opel's name for the Volt). GM got the hybrid right. If I had had the money I would have cancelled my ECO MT delivery and driven home in a Volt instead.


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## Aussie (Sep 16, 2012)

obermd said:


> Aussie,
> 
> If you get a chance, test drive a Volt or Ampera (Opel's name for the Volt). GM got the hybrid right. If I had had the money I would have cancelled my ECO MT delivery and driven home in a Volt instead.


We have the volt plug in hybrid here but I really am not interested in electric vehicles. I drive an electric forklift for a living and by the end of the shift I have had enough. I know it is not the same but I love driving a normal vehicle when I travel home. My previous car was a 3.8 5 speed manual commodore with both LPG or petrol fuel at the flick of a switch. Because of the price of LPG it was really cheap to run and if you went on a trip you could go at least 1,500km between fill ups, that's 900 miles +.


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## XtremeRevolution (Jan 19, 2012)

Psychomidgit said:


> Unless the Cruze is built differently than other vehicles it will over time. And yes they account for ride quality but that is not the only reason why they have recommended tire pressures. It's also because tires are an important part of your suspension that take in quite a bit of road shock to protect the other components. By overinflating your tires you are reducing this property, therefore putting more stress on your suspension which overall will reduce it's lifespan. As for LTZ's, it's been accounted for and they've obviously researched how it affects the suspension on that model and figured that it will hold up under normal driving conditions, but, the suspension will wear more quickly than the other models.
> 
> Where was this tested? I've seen plenty of tires blow out due to load and also not at 200psi. I will not argue that it is more common that blowouts are due to under-inflation, over-inflation has been a cause also. Over-inflation raises the possibility of puncturing, separating plys, and bubbles in the sidewall. It also increases heat expansion due to the higher pressure the tire will be under when warmed up.


I do want to point out that this has been already discussed extensively. I'm talking 10+ pages of discussions. 
The spring height and shock stiffness is the only difference in the LTZ, which are made as such for performance characteristics. If you think an Eco tire at 51psi will cause consequentially more wear than an LTZ tire at recommended sidewall (keeping in mind the unsprung weight is MUCH higher), you are fooling yourself.

Blowouts are not caused by tire pressure. This is a fact. Blowouts are causes by road debris and dry rot, the latter of which is actually reduced by running tires at max sidewall. 

Over-inflation doesn't cause the separating of plies. That will be caused by under-inflation. It would behoove you to read the rest of this thread where the exact same scenario was noted as a result of the Ford/Firestone fiasco where the tires were UNDER inflated. The resulting rolling resistance causes enough heat for the tread compound to suffer permanent degradation and even the plies to separate under load. 

Heat is caused by rolling resistance. The lower resistance you have, the less heat you will have. Lower pressures = higher rolling resistance. This has been well documented here. None of this discussion is new. 

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## Psychomidgit (Jun 9, 2013)

Ok, since you insist I'm off I will go through my manuals and double check since what I have stated has come off of the top of my head and from my past experience and training from the schools that I've been through. As I stated in my previous post, I will not argue that under inflation will cause those things also because it is a known fact that it can. But, as stated before, over inflation can also cause the issues I stated. There is a reason that the tires have a max psi level, not just because of the higher pressure but because the tires will have less resistance to the road shock, aka pot holes. And yes I am well aware that under inflation is worse for shock, but that doesn't negate what I'm saying about over inflation.

With the LTZ, re-read what I said in my last post. I stated that it will put more shock to the other components due to the higher amount of transfer than the other models. I did not compare the LTZ to yours


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## XtremeRevolution (Jan 19, 2012)

Psychomidgit said:


> Ok, since you insist I'm off I will go through my manuals and double check since what I have stated has come off of the top of my head and from my past experience and training from the schools that I've been through. As I stated in my previous post, I will not argue that under inflation will cause those things also because it is a known fact that it can. But, as stated before, over inflation can also cause the issues I stated. There is a reason that the tires have a max psi level, not just because of the higher pressure but because the tires will have less resistance to the road shock, aka pot holes. And yes I am well aware that under inflation is worse for shock, but that doesn't negate what I'm saying about over inflation.
> 
> With the LTZ, re-read what I said in my last post. I stated that it will put more shock to the other components due to the higher amount of transfer than the other models. I did not compare the LTZ to yours


For the record, within maximum sidewall limits, I do not consider any pressure over-inflation. 

The reason I keep bringing up the LTZ is to point out that there are much worse things you can do to add stress to your suspension components, which the manufacturer did. Those 18" wheels are very heavy. If GM didn't care to make those wheels especially light, it is probably because the difference is negligible. 

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## JWishnok (Dec 15, 2012)

XtremeRevolution said:


> In my mind, the rim is more expensive to replace than the tire, especially with the Eco and LTZ trims.
> 
> Sent from AutoGuide.com App


My rim to get replaced i think was $250 or $275 that's just one lol.


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