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.