Simon C

Hey folks,

I checked archives but couldn't find the specific information, so here goes.

What is the optimum HOT tire pressure offering the best grip when using the Goodyear F1 Super Car tires on stock Z51 wheels?
(Road Course Application)

I ran the car at NHIS a few weeks ago (temps in Mid 70s) and started the tires at 30PSI. After the session the tires were up 6-8PSI all the way around. I noticed at the end of the sessions the tires looked a little cooked/melty so I am concerned that 38PSI is too high.

I called the general access number at Good Year but never got an answer.

I would appreciate all suggestions.

S.

mlongo99

I've been shooting for 38psi hot. At 40 they feel greasy. What I found is that due to the nature of the track, 2 tires look ok, but 1 of those is begging for more negative camber. 1 tire is kind of torn up, and the 4th one is even more torn up. Also, the centers are worn down more than the edges. I'm not sure if that's from the track or the street though. I'm not sure exactly what you mean by "cooked/melty", maybe I just haven't seen that.

Dave S

36-38 psi hot should be about right....try starting at 28 cold & see what that gets you. Keep in mind that all the variations of ambient temp, track temp, track layout, style of driver, etc, etc, play into accumulated tire temperature & resultant pressure.

kelp

38 is good pressure. Just came back from VIR yesterday. Especially if the track is hot.

reddevl

never ever start at 28 psi cold. you could seriously get hurt.

on track like www.grattanraceway.com the straight away is more than 1/4 mile long if your tires are barely heated up you are in serious trouble as the cars can hit 125+ on that straight away and with the lower pressure your rearend will definetly start stepping out of line. Always start at 32psi cold and with in a 15 minute session you wont get past the 40 psi barrier. read at tirerack.com it shows for the supercar tires what cold pressure do u have to be at to run the high speeds.

WA6AIK

Tire rack rates the Goodyear Eagle F1 supercar tire at max 44 lbs.
The concept is to keep the tread flat on the ground and when the pressure is raised much over 31 lbs the tire tread will curve and only the center of the tire tread touches the ground. Thats why the center wears faster then the sides.
The max pressure rating is for the load being put on the tire so that you can maintain the tread being flat. If you notice in F1 racing the Japanese teams are using automatic air filling devices mounted on the backs of some of the pit crew. These devices will automatically increase or decrease the air in a tire to a specified point because they want to maintain the flat tread contact. Now they go from 0 to 100 in less than 4 seconds. So they heat the tires with warming blankets.
Starting with a 28 psi tire and then doing a burn out to heat the tire will work. Once you get over the point where you curve the tread you are losing grip. The tire info plate on the door jamb shows 30 or 31 for the stock tires and that is on a 186 mph vehicle.
I wonder what the pressure would be if you ran 25 miles on the autobahn at 150?

AutoCutter

34 cold all four tires. Mine will heat up to 37 pounds with a 30 minute session, up to 38 pounds after the second session. I tried 36 cold, but never liked the feeling, and more to the point, the lap times increased almost by 2 seconds.

69and88

This is a somewhat subjective and very track dependant question, but from my experience during the C6 tire development process, around 35 psi hot as a starting point is best. The 30 PSI recommended placard inflation is the pressure at which the tires were designed and optimized for the best all around performance, that is, wear, ride, handling, etc. and is what should be used on the street The 44 PSI commented on is simply the maximum pressure the tire can be inflated to (stamped on the sidewall). However, for track use, increasing the pnuematic stiffness is needed to prevent rolling over onto the shoulders and loading the outside of the tire footprint (contact patch) too high. You know, get out your shoe polish and see how far down the shoulders you are running. The shape of the Supercars (all C6 tires) takes into account dynamic handling, to reduce outside shoulder pressure and maintain a more uniform footprint during handling, but an increase in pressure is need for extreme track type situtations. The issue that some are running into at too high a pressure is the footprint is rounding out too much (i.e. basketball shaped instead of square shaped), resulting in using only the center of the footprint which will heat up quickly and become "greasy", basically you are inefficiently using the tire footprint. However, a little bit rounder than square is good for the track, but not too much. This is where each track, conditions, temperature, etc, will play a big impact on just where your inflation needs to be for optimum preformance, so start round 35 f/r and go from there. The Supercars tend to rise in pressure when hot a little quicker than ordinary tires due to the tread compound (high grip, max dry compound) as any ultra-high performance tire, but compensate with pattern and reduce tread depth. In Autocrossing, although different than a track, I found on my C6 that 36-38 front and 30-32 rear worked best. What this did was keep the back planted/increased traction (squarer footprint better for rear power down) and rounded out the front a bit to prevent over working the front shoulders, in escence, reducing rear oversteer under power, and increase front corner grip (reducing understeer), resutling in a better balance for the course I was running. In actuality, since the front and rear tires are different sizes, they were tunned to be this way even at the usage inflation of 30 PSI, for optimum all round performance. This is what you want to target and consider each time out at the track. Hopefully this gives you a little better understanding of how the tire pressure and the footprint of the Supercar tires can be used to tune handling for your individual track, conditions, temp, etc...... just keep in mind, we are talking specifically the C6 base Goodyear Eagle F1 GS-2s, Z51 Eagle F1 Supercars, and the C6 Z06 Supercars, as other tire brands, sizes, are developed and can perform/react differently to changes in inflation pressure.

John Shiels

remember you tire creates heat from changing shape and flexing. To low and it is making a flt spot under corner loads and losing it's natural shape. It is like bending a piece of metal it gets hot. Street tires are thicker and develop more heat as they flex. Also on a car running a road course the brakes contribute significantly to heating the rim and tire. Years ago I ran Michelin Pilots and easily developed over pounds in short order. Then all the bells were going off from the TPWS. Probably started at 30 cold. Nitrogen fill will help but you need to do it 4 times to each tire to get most of the air out not one fill up.

06corvette

I do 29 COLD and it goes till 33 hot all around.
This is the best thing for me.
good luck