ish3

36 psi front, 38 psi rear.......don't ask me why, it just *feels* right.

JohnMetro

Could someone please explain why 16" have more pressure in rear, 17" have same pressure front and rear, but then 18" go back to higher pressures in rear???

Jeremy Pinsly

I run 34 psi front, 36 psi rear in my 17s

JasonAndreas

Porsche hadn't approved the use of 17" wheels on the 964 until the summer of 1991. And with the approval came the suggestion to install replacement steering stop washers, Porsche part no. #964-347-325-02 (MSRP $30.69USD)



and to check for enough clearance between the fender's metal edge and the front tires.

ilko

Hey Jason, is there a particular build date where the changes happened? I have a late March build MY91 with (what looks like) factory shaved fender metal edge and no rubbing whatsoever. I don't know if I have the 10mm steering stops, but it feels like I do.

boxsey911

Well, I would say the new pressures made quite a difference today. Although I couldn't go anywhere that allowed high speeds (legally ) the car felt much more connected to the road and didn't jump around as much over bumps .

It'll get a much sterner test in just over a month's time when it gets its first track outing . Thank goodness I saw this thread otherwise after a few hot laps the 44 psi could have reached nearly 50!

Thanks guys, Steve

JasonAndreas

Sorry I can't find a build-date or VIN listed anywhere so the only thing to really go by is the general time frame of the TSB?

ilko

The TSB was issued in the Summer of 91, correct?

drodg

After putting the 17'" cup wheels (Mille's) and Bridgestone RE750's on my 89 C4 I can't believe the difference in handling. I am running 36psi all around and the car just handles much better than the 16" wheels and tires. It feels like some of the understeer is also gone but that could be my imagination and roads I drove on this weekend.

DWS964

What is the recommended pressure when using 225's on the front instead of 205's? I would guess that the original spec of 36 psi should be reduced by 1-2 psi.

I just purchased a set of Cup I replicas 7.5" / 9" from a fellow Rennlister with a set of Bridgestone S03's mounted, 225/45 front 255/40 rear. I love the look of the new wheels, how they fill out the fenders better than my original 16" Cups. The handling is better, but I haven't really put it to the test. I will post pics soon.