Going to the Track

[spudd001]

I am going to the track this Friday for the first time in this car. Wanna see what she can do with what shes got. What would you recommend the rear tire pressure to be for the best launch? Wish me luck!

If your from the Dallas, TX area... you need to come out to Ennis, TX Motorplex for Fast Fridays, its a blast!

 

[Joe Fan]

I would go with 38 pounds in the front and 28-32 in the rears (depends on how cool the track is, at night drop pressure). I tried 28-32.5 in the rears and 32-38 in the fronts and my best run was with 38 pounds in the front and 32.5 in the rear. I have heard you could drop the pressures down to 25 in the rear to increase the contact patch but dropping it too could reduce the contact patch due to cupping. I am not sure it makes much of a difference with radial street tires.

Probably the best answer to your question is to do a burnout somewhere the day you are going to the track. If the skid mark is dark on the outside and too light in the middle, then increase the tire pressure until the skid mark is solid black and even. If the skid mark is too light on the outside but darker in the middle, you have too much air pressure so decrease your tire pressure until it is a solid black mark. Let me know what you find.

 

[stang8urimport]

I would go with 38 pounds in the front and 28-32 in the rears (depends on how cool the track is, at night drop pressure). I tried 28-32.5 in the rears and 32-38 in the fronts and my best run was with 38 pounds in the front and 32.5 in the rear. I have heard you could drop the pressures down to 25 in the rear to increase the contact patch but dropping it too could reduce the contact patch due to cupping. I am not sure it makes much of a difference with radial street tires.

Probably the best answer to your question is to do a burnout somewhere the day you are going to the track. If the skid mark is dark on the outside and too light in the middle, then increase the tire pressure until the skid mark is solid black and even. If the skid mark is too light on the outside but darker in the middle, you have too much air pressure so decrease your tire pressure until it is a solid black mark. Let me know what you find.

Huh? lol. Decreasing the rear tire pressure from stock will not really help. These aren't the good old days of bias-ply tires. The sidewalls are not going to wrinkle and give extra contact patch.

As far as the burn out thing.... All tires grow with speed (centrifugal force) so doing a burn out and looking at the skid marks will do nothing. It will always look like they are over inflated (if you would even beable to tell the difference)

Nick

 

[Joe Fan]

Huh? lol. Decreasing the rear tire pressure from stock will not really help. These aren't the good old days of bias-ply tires. The sidewalls are not going to wrinkle and give extra contact patch.

As far as the burn out thing.... All tires grow with speed (centrifugal force) so doing a burn out and looking at the skid marks will do nothing. It will always look like they are over inflated (if you would even beable to tell the difference)

Nick

The information I posted above is what I have experienced firsthand or what I have read and heard from others. I did state that lowering tire pressure on street radials probably doesn't make that much of a difference. But it has made a difference for me when I have done this at night. My times climb to low 14s at my track at night. I lowered my pressures to 2-4 pounds and was back running high 13s again. But under daylight runs, dropping pressures had no real noticeable effect.

The lowering of pressure may not increase the contact patch but should keep more of the contact patch on the track surface due to the centrifugal force you mention when a tire is at speed. This is why I think it does help some in certain situations. Also, the tire pressures increase a 1/2 pound to a pound after several runs because of heat.

 

[Hoboattacker]

I've heard Ennis is like glass. Tire pressure...eh, I don't know where I stand on this one. I've cut a 1.9 60' with 36lbs in the tires and cut a 1.9 with 28lbs in the tires.

Basically, work on your clutchwork. That's where you're going to get your times. Learn to slip the clutch and all that good stuff (if you have a manual). If you have an automatic...just floor it.