Track Day Tire Pressures'

[IMLost]

I'm going to the Deep South Cobra Club track day and have not put my car on track before. I run 28 psi tire pressure on the highway. What pressure is recommended for tracking our cars?
Ideas? I'm thinking 20 to 22?

[fastd]

i think it may depend on the tire brand/type.

[snakeeyes]

I agree with fastd. You might use 24 pounds as a starting point and look at wear and pressure increase after a few laps. I've never tracked any of the Cobras I've owned but have tracked my Lister replica pretty extensively. Frankly the biggest problem was getting the tires up to temp and keeping them there because the car is so light. The typical Cobra replica is probably 300-400 pounds heavier, but still light compared to anything made today. It's been a few years but IIRC when I was running on R-compound tires (Kumho V710 was my usual), I would start pressures in the very low 20s and then reassess as the day went on.

[1795]

As others have said, it will be tire specific. When I race my cobra with Hoosier Vintage TDR's I run 17 lbs in the front and 16 lbs in the rear, but they are biased ply tires. Just be careful and slowly build up speed. Bias ply tires will let you know when you are losing grip, radials have better grip, but they either have grip or they don't. You may not know when you are on the edge of the tires breaking loose. I wold ask other people at the track who are running the same tire, or post here which brand you are using.

Jim

[1795]

I would also add this suggestion. When you go out on your first lap you will want to warm your tires up so that they grip better, do not run hard on cold tires, you increase the likelihood of an accident. Go at slow to moderate speed on the straights and weave the car from side to side. This will build heat into the tires and increase grip. Make sure that you stop weaving prior to corners. If you are able to check tire temps, that will help you find the right pressure. Yo want even temps across the face of the tire. Take a temp at the outside, middle and inside of the tread on each tire. Camber will affect the temp readings, as the more camber the more one section (inside or outside) of the tire will be contacting the pavement then the opposite side of the tire. High temps in the middle, as opposed to edges, suggest over inflation. Lower temps in the middle as opposed to edges suggests under inflation. Temps do not need to be exactly the same, you just want to address differences of 5 degrees or more.