The table below suggests tire inflation pressures for competitive driving. Tires should be reset to normal inflation pressures when returned to the street. These recommendations should be used as a starting point. Pressure can be adjusted to match the driver's preferences. Adjust pressure in 2 psi increments.

Type of Vehicle	Position	Pressure
Front Wheel Drive	Front Rear	35-45 psi 30-40 psi
Front Engine/Rear Drive	Front Rear	35-45 psi 30-40 psi
Rear Engine/Rear Drive	Front Rear	35-45 psi 35-40psi

When racing on D.O.T. approved tires air pressure is a major consideration in tuning the handling of your car, especially in cases where suspension adjustments are limited. The chart below shows some of the changes you can make to change the balance of the car.

Guide To High Performance Handling

Adjustments	Decrease Understeer	Decrease Oversteer
Front Tire Pressure	Higher	Lower
Rear Tire Pressure	Lower	Higher
Front Tire Section	Larger	Smaller
Rear Tire Section	Smaller	Larger
Front Wheel Camber	More Negative	More Positive
Rear Wheel Camber	More Positive	More Negative
Front Wheel Toe	Toward Toe-Out	Toward Toe-In
Rear Wheel Toe	Toward Toe-In	Toward Toe-Out
Front Wheel Caster	More Positive	More Negative
Front Springs	Soften	Stiffen
Rear Springs	Stiffen	Soften
Front Anti-sway Bar	Soften (Thinner) (or move towards outer holes)	Stiffen (Thicken) (use inner holes)
Rear Anti-sway Bar	Stiffen (Thicker)	Soften (Thinner)
Weight Distribution	More Rearward	More Forward
Front Springs	Soften	Stiffen
Rear Springs	Stiffen	Soften
Track	Widen Front track	Reduce Rear track
Front vehicle height	Lower	Raise
Rear vehicle height	Raise	Lower

To get even tire wear when using D.O.T. tires you must be very careful not to use too low of a tire pressure. The Hoosier Radials can wear unevenly if underinflated and seem to work best at much higher pressures, such as the mid 30s to as high as 50 psi. Underinflation will cause a thin ring of wear at the very edge of the tread. The best results on the Hoosiers seem to come when they are properly inflated, on fairly wide wheels, and with a good amount of negative camber. If properly inflated, these problems can be avoided. Probably the biggest adjustment you can make to improve tire wear is the driver. Avoided sliding the tires, locking up the wheels under braking and drive as smooth as possible.

TIRE PRESSURES IN THE RAIN

For both autocross and road racing, increase tire pressures 6-10 psi from what you would normally run in dry conditions. Hydroplaning occurs when a wedge of water develops between the tire and road surface. This wedge can actually lift the tire off the road and eliminate traction. Increasing the pressure rounds the profile of the tire by decreasing the deflection of the tire. This results in a smaller contact patch - narrower and shorter. It also helps keep the grooves in the tread open so they can channel the water out from under the tire.