Tire pressure

[GXP2006]

I have an 06 GXP which I've had since new. I've always put 30psi (cold) air in the tires. My tire guy (who comes from a racing family) has suggested I run 28psi to stop the tires wearing out in the center. Yet the GM sticker clearly states 30psi cold temp.
Has anybody had success running their tires on the Grand Prix at a different pressure?


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[stealthee]

I run my tires at 35 psi and have no issues with center wear.

[Fivefingerdeathpunch]

28 won't help it any. It's just a nature of the beast with those GXP's.

I'd run 35psi too or swap tire brands and see how they wear.

[cheatah faheatah]

Lower pressures result in higher rolling resistance = poorer fuel economy (mpg or kmpl?) Handling suffers too because of reduced sidewall stiffness. Only plus I see is a more comfortable ride in a straight line.

[nox]

Cheap tires are the Bane of the GXP. I'm currently running at 32 PSI with no uneven wearing issues.

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[GXP2006]

I just installed the Michelin Pilot Sport AS3+ tires 2 days ago. So far they seem to handle better than the Yokohama Avid Envigors that I had on. I'm going to experiment with higher pressure & see how it goes

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[GXP2006]

I run my tires at 35 psi and have no issues with center wear.

Good to know. How many miles have you put on at 35psi?

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[GXP2006]

Cheap tires are the Bane of the GXP. I'm currently running at 32 PSI with no uneven wearing issues.

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I agree. You get what you pay for (usually)

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[cheatah faheatah]

Lower pressures result in higher rolling resistance = poorer fuel economy (mpg or kmpl?) Handling suffers too because of reduced sidewall stiffness. Only plus I see is a more comfortable ride in a straight line.

If you need to even out tire wear, just corner faster more often

[LeadfootCJ7]

I have never followed the window stickers. I study each new set of tires and adjust pressure until I get a proper contact patch and footprint. On my GXP I have run anywhere from 35-41 on my fronts. The rears are typically 33-38. There is less weight in the back so I don't find I need as much air in the rear.

[MonzaRacer]

Ok so let me impart some info from old time tire guys ( even older than ME) . On radials to get better life remember two things, your cold temp should run 80% of tire max psi, proper dynamic balance, and remember to rotate tires regularly. Oh and NEVER BUY DIRECTIONALS.
When rotating tires always cross fronts to rear then bring rears straight forward. On later model cars feathering to a degree with more local turning, in NORMAL. The reason for proper rotation as I stated is too break the wear patterns induced by your car/driving style. Also when looking at the factory specs, also read your tires. If you do driving in and around town and you have inner edge wear (smooth with limited feathering) means your car/driving style needs less negative camber. If your doing more distance driving and have same issue same thing. Prefered camber SHOULD wear and handle decent. BUT will still be a trade off for either action. You want better handling, you keep drooping the camber negative till you get no track time increase with identical tire temps. Critical tire temps SHOULD BE uniform across tire for longevity but if higher inner temps with more negative camber result in faster car and no tire blistering your good.
More positive camber results in better tire wear uniformity.
NOW, when racing tire pressure should go DOWN, HIGHER TIRE PRESSURE WILL LOOSEN THE HANDLING UP.
On the street I honestly like seeing 44 to 51 psi tires no lower than 40 psi. If any tire guy tells you to run low pressure in a 51 max psi tire ITS HALF FLAT DUMKOFF. Using 80% rule ie at least 80% of max cold inflation.
The door spec has no clue what tires you installed. But it should be minimum regardless. But is too low.
And yes wide tires wear in center, especially if the tires are wider than the wheel.

[GXP2006]

If you need to even out tire wear, just corner faster more often

Lol

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[GXP2006]

I have never followed the window stickers. I study each new set of tires and adjust pressure until I get a proper contact patch and footprint. On my GXP I have run anywhere from 35-41 on my fronts. The rears are typically 33-38. There is less weight in the back so I don't find I need as much air in the rear.

Any problem with the tps monitor?

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[GXP2006]

Ok so let me impart some info from old time tire guys ( even older than ME) . On radials to get better life remember two things, your cold temp should run 80% of tire max psi, proper dynamic balance, and remember to rotate tires regularly. Oh and NEVER BUY DIRECTIONALS.
When rotating tires always cross fronts to rear then bring rears straight forward. On later model cars feathering to a degree with more local turning, in NORMAL. The reason for proper rotation as I stated is too break the wear patterns induced by your car/driving style. Also when looking at the factory specs, also read your tires. If you do driving in and around town and you have inner edge wear (smooth with limited feathering) means your car/driving style needs less negative camber. If your doing more distance driving and have same issue same thing. Prefered camber SHOULD wear and handle decent. BUT will still be a trade off for either action. You want better handling, you keep drooping the camber negative till you get no track time increase with identical tire temps. Critical tire temps SHOULD BE uniform across tire for longevity but if higher inner temps with more negative camber result in faster car and no tire blistering your good.
More positive camber results in better tire wear uniformity.
NOW, when racing tire pressure should go DOWN, HIGHER TIRE PRESSURE WILL LOOSEN THE HANDLING UP.
On the street I honestly like seeing 44 to 51 psi tires no lower than 40 psi. If any tire guy tells you to run low pressure in a 51 max psi tire ITS HALF FLAT DUMKOFF. Using 80% rule ie at least 80% of max cold inflation.
The door spec has no clue what tires you installed. But it should be minimum regardless. But is too low.
And yes wide tires wear in center, especially if the tires are wider than the wheel.

Well that's food for thought. I wish I could rotate the tires. Unfortunately the fronts on the GXP are 255/45 18 & the rears are 225/50 18. So no rotation is possible. These new PS AS3+ tires handle great so far so I'm going to see what happens with higher pressure.
Thanks for the help.

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[Fivefingerdeathpunch]

The TPMS won't go off with different pressures like that as they not high enough to trip the light and not low enough to trip the light. The nice thing about GM TPMS systems is that they don't even care if you run different amounts of PSI from front to back or left to right so long as it's in the threshold of what the system wants.

Some vehicles are very picky and clearly want more or less in the front or back and will trip the light even when only very few psi above or below the sticker. Like my truck states 35psi front and rear, I can have them all the way down to 27psi before the low warning light comes on...