Tire pressure
#1
Rennlist Member
Thread Starter
Join Date: Oct 2006
Location: Colorado
Posts: 43
Likes: 0
Received 0 Likes
on
0 Posts
Tire pressure
Just purchased a '95 C4 Cab with Michelin Pilot Sports 205/50ZR 17 on front and 255/40ZR 17's on rear. Factory manual says 36# all around for the C4. Any thoughts on this for street driving? Thanks, Topcot
#4
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
993s with 17" wheels call for 36 front and rear. I found that worked fine for my NB with 17s.
18" wheels will be 36/40, or 36/44 depending on the wheel and tire.
18" wheels will be 36/40, or 36/44 depending on the wheel and tire.
#7
Nordschleife Master
I also have been running 36psi in the front 225/40/18 and 44psi in the rear 285/30/18 tires.
Just curious as to the logic behind why Porsche recommends the higher rear tire pressure with 18 inch and not with 17 inch wheels?
Just curious as to the logic behind why Porsche recommends the higher rear tire pressure with 18 inch and not with 17 inch wheels?
Trending Topics
#8
Nordschleife Master
bump...
#12
Rennlist Member
In general, the wider the tire, the more pressure is required to keep the tread wear even. Too low, and the margins of the tire will wear more quickly, too high and the centre will wear prematurely. Given that 18" tires generally run with 265-285 tire widths, vs. 255 for 17", that probably explains the difference in recommended pressures.
With 285/18", I usually run 40 in the back - a good balance between grip/ride comfort/wear, and with 225/18, 34-36 depending on temp.
With 285/18", I usually run 40 in the back - a good balance between grip/ride comfort/wear, and with 225/18, 34-36 depending on temp.
#14
Rennlist Member
I am on my second set of 17 Pilot Sports and have run 34-36 psi front rear - doing that the wear was very even across the width on the first set of tires even at aggressive alignment settings. For street use anything above 36 was noticeably harsher and not recommended on the 17 in. wheels regardless.
bill
bill