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Old May 1st, 2017, 06:29   #27
shepner
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Join Date: Mar 2006
Location: Milwaukee, WI
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Originally Posted by Petra's cousin View Post
Looking to take our 2011 TDI wagon out to AutoX in a couple of weeks, any guidance on what kinds of tire pressures to start with? I'm running 235-45/17s (Pilot AS3+).
Sofar Ive found that "it depends". With the Michelin super sports last year, I slowly kept bumping up the pressure as I got more aggressive to keep the sidewalls from rolling over. Adding the rear sway bar made me change the pressures as well (a bit less overall). I need to check my notes but I believe I was at ~42psi in front by the end of the season. This year I have a set of Bridgestone RE-71R which have significantly stronger sidewalls (and very sticky). I had started out with the same pressures and found the center was getting hot and not the outer edges and so I bumped down to 40psi front, 42PSI rear. Over this last weekend at a very cold/wet HSAX drivers school I was running 38PSI front, 42PSI rear which felt good but I didnt take any temperature readings. Ill try that as my starting point in my next event.

If you take a silver sharpie and make a mark from the tread onto the sidewalls, you will get a good indication of how much your sidewall is rolling. If its too much, increase pressure.

The general recommendation Ive heard is start at +3PSI over recommended and adjust from there. If/when you want to do something about the understeer problem, raise the pressure in the rear until it can start rotating and/or add a rear swaybar.

stephen
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