Competition Tire Pressure

The table below suggests tire inflation pressures to be used during competition. 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 lb. 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) Stiffen (Thicken)
Rear Anti-sway Bar Stiffen (Thicker) Soften (Thinner)
Weight Distribution More Rearward More Forward

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. Underinflation will cause a thin ring of wear at the very edge of the tread. 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.