What is a good pressure to lower the stock peralli's on the SS/SC's too? I'm going to the track next week, and I believe if i lowered the tire pressure I could get a better 60'.

 

try in between 22-26 psi. i get very little wheel hop compared to having 35psi in the tires. Plus i think the tires will grip better. One bad thing is that i think you will have a lower trap speed when you lower your tire pressure.

 

To get the optimum tire pressure for the dragstrip the best way is to check your "rubber" marks on the ground after some wheel spin. I used to read all the mags that said to lower your pressure -- this is for true drag racing tires not street tires. I used to automatically lower the pressure on my street tires when I went to the dragstrip -- until I found that my tires were leaving "rubber" only on the outside edges. I then increased pressure to the point that I left a "full" width mark. That was the point that the tire was biting the best it could. I found from doing checks this way that the best pressure was very close to the recommended tire pressure -- usually only 2 to 4 PSI less. Try it and you'll see yourself.

 

i lower to 30 psi here works better.

 

will it still benefit an automatic car that doesnt really experience wheelhop to lower the pressur below 30psi? im going next wed too

 

I've heard now that it is good to up the air pressure in your rear tires and not to worry about the fronts air pressure because they are street tires.

 

when i first get to the track I lower the rears to 20 and raise the back to 45
someitmes I go down to 17

there are a couple reasons to explain why you raise the pressure in the rear tires. one is it helps stiffin up the rear of the car to decrease front to rear roll taking weight of the front end. and some say that the rear tires will produce less drag if over inflated.

 

Street tires have stiffer sidewalls than drag race tires. If you reduce the pressure too much the sidewall begin to hold up the outsides of the tire, and the center tread actually folds up, so that you are essentially riding the side walls and not using the entire tire. You need all the tire's tread to reduce wheel spin. Additionally, underinflated the front tires increases the roll resistance significantly at higher MPH so you are doubly defeating your primary purpose -- to get to the end as fast as you can. If you start with wheel spin when your tires are properly inflated lower the tire pressure by 2 PSI at a time and try to spin them again; if it gets better keep deflating -- but if the wheel spin problem doesn't stop then you are simply overpowering the tires anyway and deflating the tires till they're nearly flat isn't going to help. With only 17 PSI you also risk spinning your rims inside your tire.

Slightly overinflating (up to the maximum tire pressure for safety sake) the rear tires decreases the rolling resistance -- Just think of riding a bycycle with underinflated and overinflated tires, you need less leg power to pedal with full air pressure Vs a flat. I'm not sure overinflating the rear tires helps with front wheel drive launching but it does make sense since the fastest front drive cars use wheelie bars to allow them to launch as hard as they do.

This applies to manual and automatic equiped cars.

 

I dont know then maybe ill just go with 40 psi in the back and 30 psi in the front when i go.

 

Thank you for all your insights, I'll give the raising the airpressure in the rear tires a shot and if i have wheel spin Ill lower the front a little bit at a time.

 

For those of you that seriously lower your tire pressure (in the teens) please do yourself a favor -- put a couple of lines across your rims and tires with a marker where the tire meets the rim. Then after a run down the dragstrip check the lines to see if your rims have moved within the tires. I've personally seen this happen. You'll think that you have stopped the wheels from losing traction because you won't hear the squeeling -- but the rims will be turning inside the tire and you won't hear them when they do. And your tire balance will be out of whack...

 

Lower tire pressure to 30 psi? stock tire pressure is supposed to be 30 psi in front and 32 psi in the rear tires, at least on my ss/sc.

 

I run 36 up front and 40-45 in the rear. Thats just how i launch though.