THSCC Forums

I have completely forgot what tire pressures I was running. Any suggestions? I'm in a 1998 M3 sedan running Bridgestone Petenza RE-01R tires. Thanks!

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Phil... Now I miss the ITR and the M3!!!
1990 Honda Civic SI

50 psi on the drivers rear and passenger front, 15 psi on the opposite diagonal.

You've been visiting the wine section at HT again, haven't you?

The 15" and 16" Bridgestones seem to be at their best at 37psi. I don't know if that applies to the larger sizes and I have no idea what size you are running, Phil.

I would start with 37psi all around and adjust the rears downward if the car is pushy. You can probably get away with as little as 30psi in the rear if you're looking for balance. If the car is loose, take a few lbs out of the front but don't go much below ~35psi otherwise you'll murder the poor things.

If you can't balance it with tire pressure, start looking at the rest of your suspension setup.

Jim

Thanks Jim, I think I was running 35f/30r after looking at your suggestions. I understand what changing pressures does for fwd, but not this rwd world.

phil

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Phil... Now I miss the ITR and the M3!!!
1990 Honda Civic SI

He's not drunk (yet), he was just advising a matched perfect and staggered special setup.

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Has no responsibility whatsoever.

Sure.

As far as FWD -vs- RWD, they act about the same for the most part. The Bridgestones are particularly finicky when it comes to pressures which makes it a little trickier trying to find the optimal pressure. Unlike most street tires, their optimal lateral grip lies in a very narrow pressure range and with most relatively well balanced cars, you want to make sure the fronts stay near there.

Their longitudinal grip doesn't seem to be affected as much by running sub-optimal pressures so that is why I suggest dropping the rears if you are pushy. They actually will help put the power down better at a slightly lower pressure than where they generate maximum lateral grip so that doesn't hurt either especially in a RWD car.

A lot of people suggest raising air pressure to reduce grip and while that may work in some cases, I feel it's usually better to go the other way. It makes the breakaway characteristics more forgiving but it does tend to feel a little mushy. I'd rather drive a forgiving and slightly mushy car versus one that feels lightning quick but will bite you at any moment if you aren't perfectly smooth. The result is almost always the same on the clock so it can mostly be a matter of preference. YMMV.

Jim

FWIW, I run 37f/33r in my STi with the 01-Rs, just barely above my daily pressures of 36/32. They are by far my favorite daily driver tires for spring, summer, and fall.

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Beauty is in the eye of the beer holder.