Troubleshooting guide

Pyrometers

An even better means of evaluating pressures is the use of a digital pyrometer to measure tire

temperatures across the tread face.

These should be taken immediately upon re-entry to the pits after a little to no cool down lap. While

laser type pyrometers are easier to use, the surface probe types are more accurate as they are not

measuring a rapidly cooling surface, but they actually “probe” a bit beyond the surface of the tire tread,

where the heat is better held.

Be sure to get the temperature readings in 3 places across each tire’s tread. Since this must be done

quickly, either have a helper with a pen and paper or use a pyrometer model with a built-in memory.

Try for equal temperatures across the tire face. Temperatures will vary somewhat, from one tire to

another.

Here are some basic troubleshooting guidelines:

Too much heat in the center of the tread usually indicates too much pressure in that tire.

A cooler center usually indicates too little pressure in that tire.

Hottest on both interior edges can mean too much negative camber.

Hottest on both interior edges and a turn-in oversteer can also mean too much caster.

Too cool on the interior edge may mean a need for more negative camber.

An alternative that will come your way with experience is to simply examine the surface of the tire. A

properly inflated tire on an properly aligned chassis will have a slightly grained surface (not unlike

sandpaper). A tire that is running too cool, is a hard compound or just not being used aggressively

enough to build up heat, will be smooth with no graining. If you see smooth graining, but the interior

edge of the tire is showing small strips of rubber or much more aggressive rubber deposits that look like

the rubber is being overheated, then you are probably running too much caster, camber or there is

another condition that is overheating that edge. The point is, that edge will look different than the rest

of the tire because it is running hotter.

Varying Conditions

Understeering / Over steering:

Raise rear tire pressure about .5 to 1 psi to correct understeering and lower the inflation pressure in the

rear tires by the same amount to counteract an oversteer condition. The opposite is also true for front

tire inflation pressure. This should not be changed to extremes however, because sidewall stiffness

caused by the proper inflation pressure is needed on the front wheels. This effect may vary with

different tire designs and manufacturers.

Generally, if using soft compound tires, rear pressures less than 10 psi should not be used to correct

oversteer. Look elsewhere (hubs, rear width, axle, etc…) for a solution.