What tire pressure should I run?

[ksa8907]

Pre-canned response for customer sevice reps to distribute vs comprehensive understanding of the physics and engineering

I know where i stand.

[RedDevil]

Hmm. That's funny.
This goes against common sense thinking.

You air up the tires to max sidewall when the car is empty. Then load the car to max capacity.
What do you expect the resulting tire pressure to be?
Much higher, right?

But no. The pressure rises less than one PSI.
Because it spreads over the full volume of the tire, while the higher weight does press the suspension down and the tire harder to the pavement - but that only enlarges the contact patch by a little bit, so the total reduction of the volume inside the tire is only fractional.

In fact, the higher the pressure is, the less it will rise if you fully load your vehicle.
When your tires are underinflated then their pressure will rise some when you load the vehicle - that is, until the rim squeezes all the way down to the thread...

[gumby79]

Originally Posted by oldtamiyaphile

Even temperatures = even wear (~65PSI):

Is there feathering or cupping on the front ? Hot /cold wear pattern to match the color shift pattern on the sholder . May not be visable but rub it with a flat hand you should feal it .
Do you run the same air front and rear ?
What were tbe conditions for the IR shots .

Fronts look nice and consistent. The hoter carcass ( the part of the tire with the cords/belts/bead)is were the flex/heat generation is occurring the tread is like a cooling fin on an Aluminum heat sink for the carcass when strong forces are not applied as in eco driving. My stripes were 10°f hotter than tread 125-120° f 2° c delta and 1"up the side wall was 20 less than tread. On new sticker tires@60 psi1/4 "of sholder off the ground . With 2500lbs axle weight

the rear is center hot. EG too much air . im not complaining it works . You have proved that 2°f delta good work 3-5 psi down in the rear may improve tire life. And or balince the temp. The yellow makes a fast shift to red 1/4" out into the sholder block. Then there is a small sliver of outer sholder were the tread gives way to the carcass showing yellow hot. This is the sholder tread block lifting off the road(less tread block heat production)
---

I lost 20,000mi worth of tread when a deer jumped me @80 mph . I had the air up@80per door tag ,for towing the day before, the only time I run 80psi . So it only burned out the center. I went back and mesured the skid marks 3" wide from a 7.5" tire( less than 50% had enough contact to leave a mark)resulting in a flat spot in the center 3of 5 tread grooves that only went thump,thump when over 65psi. Till the tire wore down to aproxamitly 20k left then it would thump at any pressure that was safe, to much to handle on the front. As it was I put 75k on a set of 40k tires with recepts and fule log to back it up. Les Swabs said I owed them money on the milage warranty when they sold me a the new tires last monday.

[CapriRacer]

A couple of thoughts:

Inflation pressure is but one of many factors in tire wear. Many people report no problems using elevated pressures, but many people do!

Car manufacturers spend a great amount of time testing their vehicles at the pressure specified on the vehicle tire placard. To my knowledge, very little testing is done at any other pressure - by car manufacturers or individuals. I urge caution when using elevated inflation pressures. You don't want to find out you have a handling problem at the limit of adhesion in the middle of an accident.

[California98Civic]

I go moderately above the 44 psi rating on the sidewall of my Michelin Defenders, using tests on this site as a guide. So, under "cold" conditions (in the morning and before driving), I pump to 56psi+ because an extra 10psi seems to be the limit for big gains in fuel economy. By setting the PSI when the tires are cold, I ensure that my psi does not likely drop under 10 on a daily basis and for a while. I also know that the tires will likely not often or at all cross 60psi when hot. I used to set them at 60psi minimum. They can take MUCH higher pressures, but there is little/no benefit for fuel economy purposes. I have not had any problems doing this for six and a half years now, 12k miles per year or so. In reality, low pressure is the bigger danger because of how all the flexing as they roll heats up the tires.

Others have diff experience. You have to follow your best judgement. And always keep an eye on tire condition. Old cracking, dry-rot tires are not safe at any speed. Get rid of them.

james

[EcoCivic]

Originally Posted by JockoT

Contacted Dunlop/Goodyear today and this was their advice.

Operating air pressure is determined by the vehicle manufacturer.

If you're using the same size tire that came as original equipment on your vehicle, the proper air pressure is indicated on the door
placard or owners manual of your vehicle.

The air pressure indicated on the sidewall of each tire is the inflation pressure required to carry the maximum allowable load for
that tire. Vehicle manufacturers have invested considerable time and testing to establish an air pressure that will provide a smooth
comfortable ride in addition to an even treadwear pattern.

Our recommendation would be to stick with the air pressure established by your vehicle manufacturer.

Thank you for your inquiry through our web site.

Vanassa F
Consumer Relations

Ok, but the recommended pressure is for the average person who just wants a smooth ride. Rhat about people like me who don't care about a "smooth comfortable ride" and just care about stopping distance, handling, tire wear and gas mileage?

[mcrews]

I ran Kuhmos on my Infiniti Q45S.
it was the sticky summer high performance version.
ran 45+psi.
NEVER had center wear. Got around 44k on 3 sets in a row. I don't think they were 50k tires.
Car handled well.

[Jez77]

Originally Posted by EcoCivic

Ok, but the recommended pressure is for the average person who just wants a smooth ride. Rhat about people like me who don't care about a "smooth comfortable ride" and just care about stopping distance, handling, tire wear and gas mileage?

In Oz at least most car advertising is pushing the performance and handling of the car, I don't think I've ever seen advertising about ride comfort so I'd doubt that is the case. If car makers thought they could get performance gains by raising tyre pressure they would.

I still believe in real world conditions where roads aren't smooth, placard pressure give the best grip even if it doesn't feel as sporty.

Manufactures often set different pressures between front and rear tyres so telling people to set all there tyres to max sidewall will upset the balance of the car. You may change the car from a nice progressive understeer when traction is lost to tail happy.

I think if we are going to recommend people increase there tyre pressure we should tell them to do it in 5psi increments above placard keeping the balance between front and rear so they can see if there are any adverse affects on handling rather than one big change.

Unfortunately you never know how much you have affected things until you have an emergency. Then you may have to explain to the police why your tyre pressures where so much higher than manufactures recommendations .

[JockoT]

Originally Posted by Jez77

Unfortunately you never know how much you have affected things until you have an emergency. Then you may have to explain to the police why your tyre pressures where so much higher than manufactures recommendations .

My sentiments, exactly.

[ksa8907]

Originally Posted by Jez77

Unfortunately you never know how much you have affected things until you have an emergency. Then you may have to explain to the police why your tyre pressures where so much higher than manufactures recommendations .

I have a solution, i always drive like a crazy person so i know pretty quickly if my tire pressure is hurting or helping.