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      05-27-2010, 04:02 PM   #7
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Drives: Frozen M3, AM V8V, 991 GT3
Join Date: Nov 2008
Location: Toronto

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Originally Posted by TrackRat View Post
The max tire pressure listed on the sidewall is for DOT purposes for a fully loaded vehicle running down the hwy. It's typically 50 psi or higher on hi-perf radial pass car tires. This pressure rating has nothing to do with the operating pressure that the tire can use. You should use the pressure that gives the best performance which is typically 5-8 psi higher cold than the car maker suggests for street use but it varies and that is why a tire pyrometer is so valuable. Each tire, driver, track and vehicle are different so you adjust the tire for the best performance. If you're starting with 33 psi cold and getting to 45 psi you're probably over driving/heating the tires.

FWIW - Many FWD appliactions run well above 55 psi pressures hot without any issues. As Hoosier and BFG state, this is much better than running under inflated tires and damaging them.

Excessive heat from under-inflation or abuse can cause serious tire failures as seen in the link below.
Umm - okay - were not talking about GTI's here. Most M3 drivers that I know that track their cars generally start their tires at the psi range I stated and go for 40ish hot. And that seems to work.

I will be sure to tell the guy that got his tires to 45 that he is over driving his car He has tons of experience racing and probably the quickest driver I know. I am pretty sure he knows what he is doing.....

Not sure what you drive, but if you want to start your pressure high - that's your prerogative. Glad it works for you, but I hope you don't blow a tire.