I found I go faster at 34-35 psi in the front than I did at 38 psi. Around 33 psi in the rears works well. I was advised by a more experienced driver to set the rears 2 pounds less than the fronts and that seems to work for me.
I spray the tread with water between runs to help cool it down.
?? I typically run 32 front on 275 RE-71R and I am not rolling anything.Idk how your not rolling over the front at that pressure.
The water thing is if the tire has been heated up beyond it's optimal temp, then guys spray them with water to cool them back down between runs. Basically if its too hot to touch, it may be overtemp.Depends on a bunch of stuff like ambient temp, driving style, braking, tire load, sidewall, driving speeds, mileage, etc.
Some things to keep in mind:
More pressure for more load. Since our cars are front heavy, the front tires carry more load (generally but especially true for braking on a stock chassis).
Tires have an optimal temp, not an optimal pressure. The lower the pressure, the bigger the contact patch, the quicker the tires heat up. So for autox (slower and quicker runs), you could probably get away with lower pressure for more grip.
Any recommendations outside manufacturer spec would be "risky". Pirelli states max 50 PSI which is crazy high. Typically, 32 PSI is a common minimum. So for a quick spurt of grip, you could probably go slightly lower than 32 PSI *cold* but then consider re-inflating your tires for your ride home.
I don't know about "squirting the tires with cold water". If anything on a colder day you want to get tire warmers/coats to keep them hot.
I chalk the tires regularly and don't see much more rollover at 35 pounds than I did at 38. I was using 38-40 pounds in the front and I was much slower than similar cars. A faster driver advised using less pressure and my times drastically improved.Idk how your not rolling over the front at that pressure.
I think I have been running way too high of pressures (done to keep from rolling onto the sidewall). Last time out I was running 36-37 front and 31 rear. I'll try 31-32 and 30.Last event I ran I watched tire pressure (no heat probe yet). I aired the tires down to 31/30 cold on my gauge which showed 33/32 on the sensors, and drove to the event (about an hour). It was a very hot day - about 93 ambient. Didn't check pressure once there.
We do two three run sessions for each heat; three heats in the AM; three in the PM. After my first three runs, pressure was up to 36/34 on the gauge and nearly 40 on the sensors. Traction was gone, especially in the front. For the PM runs, I aired down the tires to about 31/30 on the gauge and went out. Big difference. Ran my best time right out of the box; thereafter I took out cones.
These P-Zeros had about 16K on them, with several A/Xs and one track day. In preparation for an open track day, replaced the P-Zeros them with some MPSS.
Rears were down to the wear bars; fronts were way past the bars.