Anir

While surfing Bob Woodman's Tire site, I noticed the following recommendations for Pirelli P-Zero C tire pressures for the 911 . He recommends 25 front / 26 rear psi cold, and 30 front / 32 rear hot. These are similar to the numbers I've seen for the Michelin Sport Cups.

Woodman's recs are significantly less than I've used in the past for my P-Zero C's (typically 30 fr / 31 rear cold, leading to about 38-39 all around hot). I intend to drop a few psi at Road America over Labor Day, to see if I pick up additional grip.

CarreraCup03

I used to run my Hoosiers at 33 psi cold to get to 40 psi hot. After many sessions with a heat gun ... I run 28 cold ... al the way around .. at WG.. with perfect temp readings. 2450 lbs 944 turbo race car.

944turbo

kary993

Anir, I do not know if the P-Zero C are like the Pirelli racing slicks, but I like to get them to 29 and 31 hot. The slicks perform very well at this pressure and the wear is excellent! Hope this helps.

Anir

Kary,

Actually, Woodman recommends the same pressures for the slicks as for the Zero C's, so you seem to be in good agreement with his suggestions. I appreciate the input from you and 944turbo.

George A

Anir,

I'm trying a set (C's) for the first time. I emailed Pirelli in the UK and they recommended 2.2 bar (32 psi) hot. I'll be at the track in three weeks and will let you know what I learned.

George

George A

Ok Anir, I finally got some info. I went to track Friday and did a session with the PZero C’s. I started out with 25/25 front/rear cold. The outside temperature was around 100F, I’m in Texas. I did about ten hot laps and came in to get a pyrometer reading of the tires.

Here are the results:

O M I | I M O
LF 150 149 162 | 190 171 185 RF
LR 166 187 187 | 181 188 201 RR

As you can tell, it was a counterclockwise track (more left turns). Not sure how to read it, but I was told the fronts did not have enough pressure. I got the hot pressure checked while I was at it and it was 36/38 front/rear. It sure looks like they need to be around 38 to 40 psi hot. I can’t imagine 32 hot.

Something is going on with my rears, but we couldn’t figure it our. The only theory was that I didn’t have enough rear camber, but that doesn’t explain the LR. My camber settings are 3.0/2.5 front/rear.

George

Anir

George,

Thank you for the post and data. You make an interesting point, because I've also felt that the tires worked well at about 38-40 psi hot in the past. I can achieve these hot pressures pretty regularly by starting with 30/31 psi cold. But, the Woodman suggestions made me question my previous technique.

Did you have someone take the tire temps immediately upon entering the pit lane after a hot lap? I've been told that the tires quickly lose their heat, and that readings are less useful if you've done a cool down lap, or drove back to your staging area before taking your samples.

Maybe, someone with more knowledge and experience will chime in. Woodman's site states 185 F as ideal and 200 F max, which makes me wonder if some of your temps are too high. Could this suggest overinflation? Underinflation?

George A

I had the temps checked right as I pulled off the track, I was still in the pit lane. I was on a hot lap right as I came in, so they had no time to cool down. The last turn is a long, fast left hander.

As far as temps go, remember the temp for the day was around 100F. I'm sure the track temperature was well above that. I'm actually surprised they were that cool.

George

David K.

I have run many sets of P Zero C and the correct hot pressure is 40 psi hot.