For Auto X 30 -31 in the front and 28 to 30 in the rear for stock F1-SC tires are a good starting point.
It also depends on your suspension set up and how agressive you are ie. how much negative camber front and rear and how much toe in in the rear.
I quick way to gauge tire effectiveness is to place 3 chalk marks equidistant on the shoulders of each tire. If you are rolling the tire (are underinflated) the chalk will start to be removed. If you are over inflated the chaalk won't be touched. Also look closely at the shoulder area of the tire and you will see some small raised triangles.....the wear patern should reach those.
Another good way is to check tire temperatures. Using a tire pyrometer measure the inside middle and outside of the tread contact area and see if there is any difference. With negative camber dialed in the inner edge will be hotter. Then a graduall decrease to the outside edge. All temps ideally should be with in 10 degrees. You can adjust with 1-2# pressure increaments. If the mid temp is higher than the edges your over inflated. If the edges are both hotter than the mid your under inflated.
If you run Hoosiers or other Race or DOT race tires your starting pressures will be higher around 40 psi, sometomes lower in the rear for traction. We use a 4 psi spread front to rear.
For the track I start my race tires 5 psi lower than AutoX because I am putting more heat into them for longer periods of time. I usually end up running lower depending on track temp and surface condition.
If you are running the GY F1-Sc's on the track you should again start in the 30 psi range cold and adjust accordingly.
Hi. Thanks for the 411. What's really wierd was when I was at BeaverRun (Wampum, PA) there was a few Vettes there.... I asked what TP were you runing on the Auto X..... the lady and dudes come back at me with 38-48 PSI!!!!!!! I was amazed and confused. I'm still confused.
I e-mailed Michelin and they said to use a pyrometer across the whole tire. If that's the case then waht temp should the tire be at.
Anyhow I ran the Auto X @ 33PSI..... I have stock Goodyear F1 Supercar tires. The sidewalls are pristine but little to no flex.
Anyone else care to interject cuz I'm still confused.
Thanks
Follow the Worm's advice..... for auto-cross keep lowering
the pressure until your wear pattern just touches the triangle tip!!!
I run 32 front 30 rear cold for high speed tracks and just "nudge" the triangles. My vette is lowered and I have added negitive Camber. See your Z06 tape!! You will have to "bleed" pressure after your first high speed session back to 32/30. Good luck!
We run higher pressures at Beaver Run because we are running Hoosiers. They like a higher pressure than the stock GY F1 SC's.
A good starting point for the Hoosier's is 44 front, 40 rear.
For the GY F1SC's a good starting point is 31 front, 28 rear.
We did some skid pad testing and found that the Hoosier settings at 44/40 were equally as fast as 36/32. The recommended National Pro Solo Champs 40/36 settings were actually slower on the fresh black top. We noww use the 36/32 settings for asphalt and the 44/40 settings for concrete, because it is grippier.
Surprisingly we found that 38/32 was faster on the concrete at the National Championships. It is all trial and erroe.
Originally posted by cholocholo41 Anyhow I ran the Auto X @ 33PSI..... I have stock Goodyear F1 Supercar tires. The sidewalls are pristine but little to no flex.
Anyone else care to interject cuz I'm still confused.
I run auto X too, so maybe I could provide some insight. The only reason to increase the tire pressure for auto X is to increase the sidewall stiffness of the tire to prevent the tire from 'rolling over' on its outer edge. The stiffer the sidewall, the more contact patch you will have under hard cornering.
The Eagle F1 Supercars on our cars already have a very stiff sidewall, and low profile, even at the stock 30 psi pressure. There is no need to increase the pressure with these tires for auto-x. In fact, I experimented with bumping the pressure up to 40 psi, and the car handled like crap. Traction was way down. I put the pressure back to 30 psi, and it was great - like a different set of tires. And looking at the tires after 6 runs, there was no wear on the sidewall, so there was no roll over going on at the stock pressure.
Now MOST street tires do need extra pressure for auto-x use, as their sidewalls aren't as stiff as the F1 SCs. For example, when I auto-x'd my daily driver ('96 Contour SE), with its somewhat cruddy Eagle HPs, I bumped the pressure up to 42 psi to increase the sidewall stiffness, and it helped tremendously. Chatting with other veteran drivers in my STS class, most were running the same pressure I was. And even with this pressure, the outer edge of my tire near the sidewall was getting very chewed up.
Bottom line: with the F1 SC's, just show up to the course with the stock pressure, and you'll be fine.
__________________ '02 Z06 , Electron Blue, Vortex intake, Magnaflow X-pipe, Corsa Indy, Stainless Works LT headers, LS1 Edit, TB bypass, Hurst, MGW Gripper, Born 2/20/02 380 rwhp / 363 rwtq
Another problem I tried to solve using tire pressure was the OVERSTEER the Z06 has. OH MY GOD! It's tremendous! Why did GM engineer such a car with so much oversteer.... so much that I couldn't see out of the windshield... felt like I was riding a wave of water on my belly. Baer Claw gave me this handy tool of info regarding suspension and handling.... it mentioned higher tire pressure in the rear and less in the front to increase understeer.
Indeed you are correct..... the Goodyear F1 Supercar tires have stiff sidewalls hence the fact that other dudes ran higher pressures to make the sidewall STIFFER didn't make sense to me. I looked at my tires and they looked normal.
Done deal then... I'm sticking with 30PSI all around for all uses. I suppose stock factory is always the best.
Originally posted by cholocholo41 Another problem I tried to solve using tire pressure was the OVERSTEER the Z06 has. OH MY GOD! It's tremendous! Why did GM engineer such a car with so much oversteer
I found the oversteer is purely throttle induced, meaning the car only oversteers if you have your foot in the gas. However, due to the light weight and tremendous torque, it doesn't take much throttle at all to put the car in an oversteer condition. Normal for a high HP, high torque rear wheel drive car.
The car itself seems to be fairly neutral handling, with just a hint of understeer when you're not in the gas.
All this power makes auto-x very tricky with this car. Just a bit too much gas too early coming out of a turn and WHAMO! Instant spin or oversteer so much you're taking out cones.
Drive it well though, and the car rewards like no other. A look at the SCCA Solo II and Pro Solo champions and you see the field is dominated by Z06s for the past 2 years.
I like this quote from Sports Car magazine (November 2002) from ProSolo champion John Ames:
"The champ also remarked that his Z06 is 'the best car I have ever owned,' high praise from someone who spent most of his career at Ford! He plans to stick with the 'Vette next year. Unless, that is, he gets the urge to buy a new one!"
So there you have it from perhaps the best autocross driver in the country.
Another problem I tried to solve using tire pressure was the OVERSTEER the Z06 has. OH MY GOD! It's tremendous!
Cholocholo,
I haven't seen this with my 02 and concur with Z06ified that the oversteer is throttle induced.
However, I did change my camber significantly before ever taking the car on the track. I set my camber max negative (about -1.7 front and -1.3 rear) without camber plates before my first track day. I ran two days at Roebling Road in Savannah on the F1s with this set up and found the car very neutral tending towards slight understeer with this setup. The next two days at Roebling I ran CCW wheels with 275 Hoosiers up front and 315 Hoosiers in the rear. With the extra rubber in the rear the car tended more towards understeer in the long sweepers but I could put the power down earlier too. I played with the pressures a little to dial out some of the understeer.
My last track day of the year was at Portland International Raceway in sort of a bastardized set up. I had put on the GM T1 sway bars but I didn't have the CCWs with me, so I ran on street tires, but a mixed setup: Kumho Ecstas (275) front and the stock F1s in the rear. I thought the car was going to be looser with this set up, but it understeered more. Not sure if it was the T1 sway bars or the difference between the Kumhos and the F1s. Either way, again, I played with the pressures until I got it near neutral and had a great day.
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Follow the Worm's advice..... for auto-cross keep lowering
I run 32 front 30 rear cold for high speed tracks and just "nudge" the triangles. My vette is lowered and I have added negitive Camber. See your Z06 tape!! You will have to "bleed" pressure after your first high speed session back to 32/30. Good luck!
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