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Old 05-26-2009, 05:38 PM
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Nevin Nevin is offline
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Location: Kalona, IA
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Re: Tire PSI for 225/45-17's

Quote:
Originally Posted by BoxerFanatic View Post
I agree with most of that, except the longest life bit...

A hard tire has less flex, and thus less rolling resistance...

But an over-inflated tire tries to "go donut" and the pressure in the center of the tread causes the center to wear faster. Conversely, under-inflated tires cup inward at the center, and all the weight and wear kills the shoulders of the tires first, unless camber or toe wears the inner shoulder even faster.

I unfortunately have experience with over-inflation. My previous car was a Ford Ranger pickup, with original goodyears... that had been over-inflated for some time, especially the rear tires. They likely inflated the tires to hold a bed full of stuff, and pumped them way up, then ran the truck with no cargo for a while, with the rear end really light.

The shoulders looked normally worn for the tires apparent age, but the center treat was worn well past the wear bars. It got a new set of dueler revos as soon as I saved for them.

I can agree that maybe the "longest life" part was maybe a bit much, because if you're not near the max weight rating, then a lower pressure can give just as much life.

When I think of "over-inflated" I generally think of people exceeding the TIRES maximum pressure, which we do also see frequently.
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