Hey guys- I have an '83 Berlinetta with a 4-barrel. I have M.T. Sportsman "I" tires on the back. I was wondering what the best air pressure would be to get the greatest traction- thanks for the help!

 

run about 20 psi on my street tires but no idea what things things can go down to

how good do they grip on normal pressure and wet weather and all that fun stuff

how long are they to last for

 

Street tires (radials) shouldn't go below 28. They work best at 32-35 psi.

The Sportsman I tires are a bias ply. Best tire pressure is trial and error. It's not a real slick and doesn't have wrinkle walls so real low tire pressures probably won't work. Start with about 26 psi and make a pass down the track. Keep dropping 2 psi out of the tires until you get your best 60 foot times. Then adjust 1/2 pound at a time either way to find the proper pressure.

Track conditions also affect tire pressures. A good sticky track can get away with higher pressures so what's good on one day may not be the best on another.

For street use get some tire chalk. It's something like a grease pencil. Go to an empty parking lot. Make a thick line across the tread and drive straight across the parking lot. Don't spin the tires. Get out and look where the chalk is worn off the tread. On the edges and the tires are under inflated. Worn out in the center and it's over inflated.

 

My radials work best (traction) at about 21 psi not 32-35 psi.