Tire pressure question

[Noey]

Maximum is not the same as ideal.

Use the sticker on the door jamb as your guide. Adding much more only increases tire wear down the middle of the tire and leads to a harsh ride, less gives poorer handling and increased wear on the sides. 41 PSI is too much.

 

[Eddie]

Technically it is PSIG and not PSI)

 

[Branson304]

I stick with the manufacturer's recommended pressure or I go up about 3 PSI from the recommendation, assuming you have stock size tires. Never had any trouble doing this. I always get pretty even tire wear assuming there's no issue with alignment or balance. That's my suggestion.

 

[HTSS_TR]

Most non high performance recommended tire pressure on door jam are for good ride with little effect on gas mileage and tire wear. First impression of a short test drive is how good(soft) or not the ride was, firmer tire(higher pressure) is usually harsher ride.

Personally, I have my tires at 2-4PSI higher than door jam, this increase tire pressure makes steering faster, even tread wear and improve gas mileage, the ride is firmer but not hash.

For long trip I increase tire pressure to about 4-8PSI above door jam, to reduce heat built up on higher speed.

My E430 recommends front 36 PSI rear 42 PSI(32, 33 normal) for high speed (above 100 MPH). Most W speed rated tires have max pressure at around 50-51 PSI.

Last but not least, it is hard to keep tire pressure at exactly as recommended because of weekly/monthly temperature change, I rather have 2-4 PSI above than below.

 

[AZjeff]

As you increase the tire pressure you decrease the contact patch of the tire. Good for a bit more mpgs, might not be the best for traction in some situations if it's taken to an extreme, like close to max pressure. You'll never know you lost grip until that emergency maneuver or standing water.

 

[Tlhfirelion]

So I rechecked the door sticker and it says 35 PSI cold. So I'm currently 6 psi over and 11 under the max pressure. I'll check it tomorrow morning when it's cool and see what reading I get. I didn't find the ride to be harsh with the slight increase but I did get better fuel economy this morning on a 50 miles drive. lol I may drop it a few PSI's. Thanks for the replies everyone, best car forum on the internet is right here.

 

[KitaCam]

Originally Posted By: OVERKILL
Originally Posted By: KitaCam
Different tires have different performance parameters and wear differently...I had what were really summer UHP tires (despite being labeled A/S) and wore perfectly evenly @ 44psi on the Camry spec'd for 29! Their max was 51psi.
The current Cooper CS5 UltraTouring (touring), max rated @ 44psi, are wearing evenly @ 32-34psi...

Should be noted that the Camry's OEM tires were 15"ers, and I'm now running 17" rims so that may account for the difference.


Why would you run them at 44 if the placard specs 29? That seems a bit odd

That generation Camry is considered the softest, most "floaty" cushy iteration....increasing the rim size, running ultra-high performance summer tread at a higher psi gave me a very firm and sure ride...it was stable in all conditions, and as reported, gave me even wear at 44psi....the Camry only weighs 3100 lbs.

 

[OVERKILL]

Originally Posted By: KitaCam
Originally Posted By: OVERKILL
Originally Posted By: KitaCam
Different tires have different performance parameters and wear differently...I had what were really summer UHP tires (despite being labeled A/S) and wore perfectly evenly @ 44psi on the Camry spec'd for 29! Their max was 51psi.
The current Cooper CS5 UltraTouring (touring), max rated @ 44psi, are wearing evenly @ 32-34psi...

Should be noted that the Camry's OEM tires were 15"ers, and I'm now running 17" rims so that may account for the difference.


Why would you run them at 44 if the placard specs 29? That seems a bit odd

That generation Camry is considered the softest, most "floaty" cushy iteration....increasing the rim size, running ultra-high performance summer tread at a higher psi gave me a very firm and sure ride...it was stable in all conditions, and as reported, gave me even wear at 44psi....the Camry only weighs 3100 lbs.


So you ran 15psi higher than spec (and the sidewall max pressure) because you used larger rims? My 4,200lb SRT-8 rolling on 20" wheels with UHP's spec's 32psi. Even my 4,100lb M5, which wore 275's on 18" rims on the posterior only spec'd 38. There is no way that 44psi on a 3100lb car yielded the best contact patch when Toyota spec'd 29 unless you were running like a 325mm tread width, which I am quite certain, you were not.

What you are seeing is the artifact of over-inflation, which is the feeling that the car is "twitchy" or some would say "nimble" because you are riding predominantly on the centre of the tread; you are literally "riding on rails" by utilizing a reduced contact patch.

If you were running significantly wider than stock tires, then increasing the pressure to accommodate that makes sense, but that doesn't sound like that is the case. And even then, 15psi is a HUGE jump.

 

[KitaCam]

one more time....empirical evidence...no internet hypothesizing...

The tire wore EVENLY shoulder to shoulder on all 4 corners....and there was no twitching, nothing but perfect traction in all dry/wet conditions I experienced.
I can't say why (other than the tread width was 1/2" wider than stock, and built for performance rather than comfort) but I can say that they worked great at 44psi.....

 

[OVERKILL]

Originally Posted By: KitaCam
one more time....empirical evidence...no internet hypothesizing...

The tire wore EVENLY shoulder to shoulder on all 4 corners....and there was no twitching, nothing but perfect traction in all dry/wet conditions I experienced.
I can't say why (other than the tread width was 1/2" wider than stock, and built for performance rather than comfort) but I can say that they worked great at 44psi.....


That's not empirical evidence, it is anecdote, hyperbole and extrapolation based on nothing more than subjective opinion. You didn't run actual track tests measuring lateral grip, handling....etc, you are just trying to justify the baseless assertion that sidewall was the "correct" pressure without any sort of science to back it up. The logic used to arrive at running sidewall pressure, if you took the time to read the information on Barry's site, doesn't add up.

It would appear you think you know more about proper inflation pressure than the Engineers that arrived at the placard recommendation by using the weight of the vehicle, size of the tire, load balance and everything else that Barry's site covers, and subsequently there isn't a hope in hades that I'm going to be able to convince you that your are wrong.

Luckily however, my obligation here isn't to convince you, but rather educate the OP, and I believe the information I've provided is satisfactory in that regard.

 

[OVERKILL]

Originally Posted By: KitaCam
Originally Posted By: OVERKILL
Originally Posted By: KitaCam
Different tires have different performance parameters and wear differently...I had what were really summer UHP tires (despite being labeled A/S) and wore perfectly evenly @ 44psi on the Camry spec'd for 29! Their max was 51psi.
The current Cooper CS5 UltraTouring (touring), max rated @ 44psi, are wearing evenly @ 32-34psi...

Should be noted that the Camry's OEM tires were 15"ers, and I'm now running 17" rims so that may account for the difference.


Why would you run them at 44 if the placard specs 29? That seems a bit odd

That generation Camry is considered the softest, most "floaty" cushy iteration....increasing the rim size, running ultra-high performance summer tread at a higher psi gave me a very firm and sure ride...it was stable in all conditions, and as reported, gave me even wear at 44psi....the Camry only weighs 3100 lbs.


I just looked up the 2005 Camry owners manual to satisfy my own curiosity.

The 15" rims on the LE spec a P205/65R15 with 29psi front and 29psi rear.
The 17" rims on the SE spec a P215/55R17 with 30psi front and 30psi rear.

So the 10mm wider tires on the factory 17's spec 1psi higher inflation pressure. Load capacity, contact patch, wear pattern, ride and handling, are of course all factored in by Toyota here. This is in-line with what I said earlier regarding 15psi being massively too high for the small increase in width.

There is also a note about periods of sustained high speed driving:

Originally Posted By: Toyota
When driving under the above vehicle conditions at sustained high speeds above 160 km/h (100 mph), in countries where such speeds are permitted by law, inflate the front and rear tires to 240 kPa (2.4 kgf/cm2 or bar, 35 psi) provided that it does not exceed the maximum cold tire inflation pressure molded on the tire sidewall.


This is due to the heat generated, which can cause tire failure, something that is mitigated by the higher inflation pressure. This is also covered on Barry's site. Amazingly, even then, Toyota doesn't recommend 44psi, or even mention it. And I assume the size above is the size you are running.

There is then yet another table that covers trailer towing. They again recommend increasing the pressure due to the additional heat generated, and to 32psi for both the 15 and 17's. The 16's continue to have the 29psi recommendation.

This should all be in your owners manual.

 

[CapriRacer]

Some technical information about inflation pressure, tire wear, and tire failures.

First, inflation pressure is a kind of minor player on the list of things that adversely affect tire wear - both wear rate and evenness of wear. There are things that have a greater effect.

Further, there are things that act counter to inflation pressure relative to tire wear - so it is possible to either underinflate a tire or over inflate a tire and still get even wear.

My experience says that dry traction is virtually never an issue with tires. My experience also says that wet traction is all over the ballpark - that not only do some surfaces have great wet traction, but others are like ice when wet! What I am trying to say here is that it is not a surprise to me to have folks not experience poor traction in spite of grossly over inflating a tire.

Also, tires can fail from underinflation, but not from over inflation - except in extreme cases!

So I can see why some folks have reasonably pleasant experiences with grossly over inflating tires - plus they get a fuel economy boost.

- HOWEVER -

My position is that anything over 5 psi over the vehicle placard pressure is not advisable.

 

[skaughtz]

It is my understanding that the suggested pressures on the placard are the minimum amount of pressure needed to support the vehicles maximum load-carrying capacity. So, since you are likely not constantly driving around with the maximum amount of weight your vehicle can handle, there is really no reason to go above those suggested pressures.

With that said, I have found that on my '07 Camry the car seems to handle and ride better at about 33psi as opposed to the recommended 30psi on the placard, so that is what I keep it at. And since I rotate my tires every 5,000 miles when I change my oil, I'm not worried about any noticeable increase in wear.

 

[ccap41]

Originally Posted By: rooflessVW
Use whatever pressure is listed in the door jamb.


+1 as well.

There's a little wiggle room for improved ride/mileage/performance but I wouldn't stray too far from that as you'll lose overall safety/performance in another category. Too high or too low will diminish overall grip.

I would wager where you had your tires put on, OP, that the 34 or 35psi was what your tires should have been set at according to your door placard.

 

[OVERKILL]

Originally Posted By: CapriRacer
Some technical information about inflation pressure, tire wear, and tire failures.

First, inflation pressure is a kind of minor player on the list of things that adversely affect tire wear - both wear rate and evenness of wear. There are things that have a greater effect.

Further, there are things that act counter to inflation pressure relative to tire wear - so it is possible to either underinflate a tire or over inflate a tire and still get even wear.

My experience says that dry traction is virtually never an issue with tires. My experience also says that wet traction is all over the ballpark - that not only do some surfaces have great wet traction, but others are like ice when wet! What I am trying to say here is that it is not a surprise to me to have folks not experience poor traction in spite of grossly over inflating a tire.

Also, tires can fail from underinflation, but not from over inflation - except in extreme cases!

So I can see why some folks have reasonably pleasant experiences with grossly over inflating tires - plus they get a fuel economy boost.

- HOWEVER -

My position is that anything over 5 psi over the vehicle placard pressure is not advisable.


Barry, you are a wealth of information on the seemingly incredibly misunderstood topic of tires and I applaud you for continuing to help and provide your expertise on these subjects in the tire section. You are a true asset to the board

 

[Traction]

As long as you keep all your tires at the base/cold pressure for any given morning temp, you will always end up with a operating temp in the sweet spot for pressure. On my C5 Vette, I can start at spec 30psi cold, and easily run down the road at 35psi with constant driving, and warmer temps later in the day. Then, it could be less on any other day. Or you can adjust for the range of operating conditions every day if you want.

 

[gizzsdad]

Originally Posted By: OVERKILL
Barry, you are a wealth of information on the seemingly incredibly misunderstood topic of tires and I applaud you for continuing to help and provide your expertise on these subjects in the tire section. You are a true asset to the board

Ditto from me!!

 

[Quattro Pete]

Originally Posted By: gizzsdad
Originally Posted By: OVERKILL
Barry, you are a wealth of information on the seemingly incredibly misunderstood topic of tires and I applaud you for continuing to help and provide your expertise on these subjects in the tire section. You are a true asset to the board

Ditto from me!!

Yes. Big thanks for all your contributions, Barry!

 

[Bgallagher]

Originally Posted By: NibbanaBanana
Originally Posted By: rooflessVW
Use whatever pressure is listed in the door jamb.


+1

Correct pressure is on manufacturers sticker in the door jam. Don't over or under inflate.


I always set my Terrain and Equinox for 36 instead of 35. Easier to read on a pressure gauge.

 

[Bgallagher]

Originally Posted By: Quattro Pete
Originally Posted By: gizzsdad
Originally Posted By: OVERKILL
Barry, you are a wealth of information on the seemingly incredibly misunderstood topic of tires and I applaud you for continuing to help and provide your expertise on these subjects in the tire section. You are a true asset to the board

Ditto from me!!

Yes. Big thanks for all your contributions, Barry!



+3 I always enjoy when you respond. I have learned quite a bit from you over the years