speedread

I ruptured a 1 inch slit in the rollover point of my p zero corsa left rear tire. The ambient temperature, acording to the national weather service, was 90 degrees around Blackhawk race track. I'm not sure how much hotter it was on the track. I set my rear tire pressure at 44 psi as stated in my manual. After one DE session, I bled off 12 psi to bring the tires back to 44. I ran another session, and bled 4 psi to bring the psi to 42. I then ruptured the tire, and had small chunking after the slit. The tread on the other tires was melted on the edge. After some helpful advise, I called Perelli and talked with a guy in racing. Especially,because of my set up ( see my signature), and because the p zero corsas are much like slicks, he said I should, (with my now ordered next set of tires), have a target of 30 psi tops in hot weather, and 32 in cool weather for all 4 tires.
His suggested cold start temperatures for Blackhawk and Road America:
left front 23 psi right front 25 psi
left rear 21 psi right rear 23 psi

I hope this helps someone else out there to avoid an accident. I was lucky and din not loose control at all. No damage except to the cooked tires.

Mike Buck

You got lucky. There is no correlation between the recommended tire pressures in your owners manual and the pressures you should put in any tire that isn’t the exact fitment that came on the car from the factory.

How long have you been using R-tires?

DGaunt

Ev3n then, the pressures in the manual adress things of concern to the manufacturer such as EPA testing, ride and durability. So, they are not what you personally might find optimal.

Because the EPA tests at the spec pressure, and end users usually run thier tires underinflated, the trend is to publish high pressures, at or near the max on the side of the tire.

I remember in the 80's Honda went the other way, specifying pressures of 24 PSI on the base Civic (not over-tired) to improve test-drive ride comfort when the suspension components were stiff in a new car. Trouble was, it would cause the tires to hydroplane something awful.

DCLee

You started at 44? That's way, way high. I don't know who your guy in racing is, but I think you should be shooting for 38-40 hot on the track. I don't think you'll never get 'em up to temp starting in the low 20s cold and running 30 hot sounds too low. I would try 26/25 or 28/27 cold and shoot for close to 40 lbs. hot. Others may have other suggestions-- I'm still new to the tires...

Lee in D.C.
'04 GT3 RS Clone

Pierre

Here the official pressures recommended by Pirelli:
kalten zustand = cold
warmen zustand = warm
v.a. = front axle
h.a. = rear axle



The pressures are given in bar, but you can use this nice converter: http://www.sengpielaudio.com/ConvPress.htm

BTW, here are the pressure Pirelli recommended back in 2002:


Based on my experience, the new values (lower) are much better.

Hope this helps.
Greetings,
--Pierre

Sanjeevan

Bob Rouleau, who has been using corsa's on his GT3 and GT2 for a long time now had experimented on the pressures and recommends 36 hot all around...I strongly recommend the same.

My last DE was my first with R-compounds, and I am using corsas on my 996 C4S as well, and I started with 30/31 cold to get 40 hot all around at mid-ohio, not really pushing too hard, but with my stock suspension I could only get -0.3 negative camber on my fronts, totally inadequate and there is significant chunking on the outer edges,...I am at this point frankly pissed off with my decision to switch to R's, I simply don't want to change my suspension to be able to get more camber, so ones I chord these on the outer edges I think I am going back to my street tires , as I am fed up with the whole thing....I switched my brakes to pagid for the higher speed, and now the damned steering wheel is shaking on braking,...no problems when it was all stock.....so, till I am ready for new suspension (JIC cross), it's street tires for me,..

Try 36 hot all around, if the camber, toe settings are ideal it should work out for you.
Jeeva

kary993

I run Pirelli slicks and the hot target is 29 front and 31 rear. You were clearly way too high particularly when you had to remove 12 pounds after a session to get to 44 pounds, my god you were at 56 pounds?

Dennis K

I'd echo the advice you're getting here to run 36 psi hot.

I think my car is about as heavy as yours (~3400 lb w/ me in it) and running 30-32 psi hot just rolls the tires under the wheels. That will just accelerate the wear and chunking on the outside shoulder of the tire.

After much experimentation, I've found 36f/34r psi hot is about the best compromise between wear and grip. I start out in the mornings at 28f/26r psi cold and I barely have to adjust them during the day. To control the chunking the outside shoulders (particularly on days >90 deg. F) I run -2.1 deg. camber at all four corners, which is quite a lot for a 928.

This outside shoulder chunking problem with Corsas is really annoying. It's the one downside to a tire which I otherwise prefer to a Michelin Pilot Sport Cup. I've seen it happen on all types of cars aside from mine, including 993TT's, 996GT2's and even Ferrari 360 Challenges when they were using it as a spec tire in that series a few years ago.

The price on Corsas at Tirerack has been so good that I've been able to afford to experiment with them and come up with some settings I can live with. If they were full price, I'd be back to Cups or on to RA-1's.

Aside from my rant, I hope this is of some help.

cosmos

I run 36 front and 38 rear HOT.

trozenhorse

any one have the pressure for a cayenne with 20's?? thanks

TheOtherEric

Speedread,

So I hope you gain 2 things from this thread:
1) pressures in the manual are completely useless, except maybe for street use, and even that's iffy.
2) Always ask either Rennlist or some other drivers about appropriate pressures if you have any uncertainty. Anyone with any experience at all would have told you to shoot for somewhere in the mid-30 psi range HOT.

You may note that the Pirelli brochure above says (in German) "hot pressure should never exceed 3.0 bar (44psi)". You should count yourself lucky you returned home in one piece, and I'm not kidding.

Super D

Did you guys shave the PZ Corsas? After having a chunked set, I spoke w/Pirelli and they said this particular tire really must be shaved prior to use. I know the RA1's and other DOT-R tires don't necessarily "require" it, but in this case I was told it's really needed. Any input on this?

Dennis K

My second set of Corsas were shaved. Chunking was reduced but not eliminated. They still had the same wear pattern on the outside shoulder, looking pockmarked where bits of rubber had torn off. This happened during summer track days with temps >90 deg F. Tire temps across the tread were no higher than 195. Subsequent track days in the winter time have resulted in far less chunking.

Sanjeevan

On my second DE with the corsas chunking of the outer edges was not as bad as I had initially thought. One of the reasons I went with corsas is they don't need aggressive negative camber like other R compds. The first time when I was on the track the leading edge of the outer grooves broke off entirely, this led me to believe it's going to worsen, but this wknd's DE at Nelson Ledges, perfect wknd., awesome driving and the tire temp. was sort of even across, there was one time the outer edges was higher by ~10 deg., but over-all the tires were excellent. Once the outer groove's leading edge broke off in my last DE, there was no more chunking this wknd. Also,36 deg. hot worked great. My suspension is stock with only -0.3 camber for the fronts, and -2 for the rears..
Jeeva

speedread

Success! In using the cold pressures listed in my 1st post in this thread for Pirelli P Zero Corsas as given to me by a Pirelli tire guy in Pirelli racing, my Hot pressures went to exactly 30psi in the front and I added 2 lbs psi in the rear to bring all tires to 30 psi for the rest of the day with no other changes. The ambient temperature was 95 degrees on Blackhawk race track. I was pushing hard, and the tires performed great! He said that the tires were designed to take initial flexing which would heat the tires and then the track temperature and heat from cornering, etc would bring the tires up to the correct 30 psi. It worked. Again the ambient temp was 95. (Reminder: the psi is for my car with my setup, not others. See my signature; and the cold psi was: Lf 23,rf 25:Lr 21, rr 23 psi).