Troubleshooting guide

Change in Atmospheric Temperature:

The general rule is to raise inflation pressures slightly as the temperature falls and lower it as the

temperature rises. If there is a significant difference between morning and afternoon temperatures,

raise the inflation pressure a little in the morning for better grip by increasing the load to generate heat.

Lower it in the afternoon to reduce generation of heat by the tire. This rule applies for summer and

winter also.

Compounds:

Tire pressure can be raised when using hard compound tires. With high grip compounds, pressures

can be lowered.

Variations in Track Surface:

Lots of rubber residue on the track surface causes greater resistance. On such a surface it is good to

lower air pressure to reduce heat generation by the tire. This holds especially true in the summer.

Rain Tires:

In wet conditions, raise the pressures significantly. However, when the track starts to dry out, a heavy

load is imposed on the tread pattern blocks of rain tires. The remedy is change to slicks as soon as

possible. As an intermediate measure you might still run rain tires, but lower the pressures.

Extreme wet conditions: 25-30 psi

Moderate wet conditions: 20-25 psi

Drying conditions: 15-20 psi

Rim Width:

Overall stiffness is changed uniformly as inflation pressure is varied but by changing the rim width,

vertical stiffness and especially lateral stiffness can be greatly varied. Furthermore, since the contact

area does not change appreciably as it does with an alteration in inflation pressure, grip remains the

same but fine changes can be made in maneuverability. For example, if the rear slide is not smooth a

wider rim than standard may be called for. However, the range in which rim width can be varied is

within +/- .5 inches (approx. 13mm).

Tire Diameters:

The external diameter (circumference) of a tire varies in response to different conditions. This must be

taken into consideration also when selecting the gear ratios. It is generally accepted that the gear

number must be changed for each 12-15mm change in the length of the tire’s circumference. This

amount of change in diameter occurs quite easily with a variation in inflation pressure and other

conditions.

Mismatched tire diameters (left to right) can have a very negative effect on handling. This is especially

true of the rear tires which should always be within 10mm of each other. Tires can be stretched in

diameter by inflating them to 40 psi or so and letting them set overnight. This is even more effective if

the tire can be left in the sun for a period of time, then recheck when the tire is let back down to proper

race pressure.