Are you getting a lot of wheel spin at launch?

 

In 2 wheel drive with ESP off and tires at 20lbs, Yes, the wheels spin too much.

 

Pardon my asking, i'm not too keen on what people do for drag racing, but by 20lbs are you referring to the pressure? If so, i've not heard of anyone running that low of a pressure. Thanks.

 

Yes, I do mean 20lbs of pressure. Without time for a lot of testing and tuning, I tried 20lbs. Once I find the best way to launch, I will slowly raise the air pressure as high as that launch will allow without breaking traction. Here is a description of the physics behind the theory.

"One very important aspect to consider with a tire is its air pressure. Raising air pressure will effectively make the tire 'more round,' so that there is less of a contact patch between the tire and the pavement; however, this results in slightly-faster speeds and less pavement grip. Lowering air pressure will flatten the tire so that there is a larger contact patch with the pavement; the resulting friction, however, will slightly slow the vehicle, although greater pavement grip is thus attained from the extra friction."

I am not sure if having the tire at a lower pressure will change the final gear ratio or not due to the tire being slightly shorter. Maybe someone with the knowledge can weigh in on the matter.

 

Ah, ok. I got you. Are you going to try a different pressure next run? If so, what pressure are you considering trying?

 

I hope you are not doing that with your every day street tires. Great way to have a tire failure at a potentially bad time. If you are serious about racing, get yourself a second set of rims for the back and some tires that are stickier. You should get a better launch and won't have to worry about damaging the tires that you are using on the street.

 

Not sure if a 1/4 mile at a time would build up enough heat to blow these tires. But enough runs over a period of time may damage them. If I ever get to that point, I will be looking to buy a car just for racing.

 

It isn't the heat that kills them, it's the damage you do to them running them way under pressure under a 3 ton truck.

 

I think I am going to try 40lbs, because I am going to launch in 4x4 with ESP off. I should have plenty of traction for the low end but with full pressure I will also benefit at the high end as well.

 

Similar times to what I ran when I went. I have a Crew Cab sport 2WD with 3.55's Only mod is the canned 93 Diablo tune. Had about half a tank of gas also. Stock tire pressure, no weight reduction, etc. Ran a 15.1. I think I posted the slip on here somewhere.