Tire pressure on road course

[olf dog]

I am heading to the track soon and would like to know what pressures others run on their stock goodyears front and back. I have an 02 with stock suspension????

[FOXBAT]

Try 34 lbs front and 30 rears for a starter.

Then monitor the pressures as the tires heat up.

From the seat of your pants, try to feel if the tires are sticky or sliding.

Sticky is good; sliding might be too much pressure, or, you're driving with your suspension control off and over driving the car, or, you're perfectly balanced and drifting through a curve.

If you're doing a DE at Road America or Blackhawk Farms, ASK any of the other corvette guys/gals there.

[DJWorm]

Just for perspective, the OEM GY F1 SC tires can be considered as an intermediate rain tire on the track. Cool dry conditions to just damp with NO STANDING WATER.

You should start with the normal pressures as indicated on the driver door jam panel, ie. 30-31 psi range. This is your cold starting pressure. Expect the pressure to rise to around 40 psi depending on the length of run and how agressive you are.

The tires will heat up during the runs. If you are doing successive runs without adequate cool down you may want to bleed off some air in increments to return to the starting pressures while hot....however if you do this then your cold pressures will be too low after a long cool down and you will have to add some pressure.

You will want to pay particular attention to the sidewall shoulders of the tires. There are little triangles on the shoulder edge and the tires should not scuff off on cornering past these. If they do the pressure is generally too low and you are "rolling" the tire. You will need to add pressure. Another method is to chalk the shoulder area in three spots on the tire and note how far the chalk is worn off.

The car will exhibit massive understeer with the OEM tires, and OEM suspension settings.

Rule of thumb is to decrease pressures to increase traction.

In wet conditions sometimes adding pressure is best. This helps prevent hydroplaning and increases water evacuation from the center channels.

When you get serious you may want to invest in the following.
- A good dial, water filled air pressure gauge (0-60 psi) from Longacre with pressure relief valve and bleed valve.
- A portable aluminum air tank from Behrent's or Longacre
- A memory tire pyrometer from Longacre. Get the probe type, the infra red meters are inaccurate.

To actually adjust the tire pressures adequately you will need to learn how to "read" a tire. You need to measure the hot tire temps across the face of the tread; eg. inside-mid-outside. The temps should increase from inside to out, but be within 20 degrees . For example: RF(I/M/O)

160/152/148 = good (12* spread I>O)
160/138/158 = underinflated (both edges higher than middle)
150/168/140 = overinflated ( mid highest)
155/158/160 = not enough negative camber, reverse spread (I<O)
175/165/138 = too much negative camber, greater than 20* spread

OEM tires will run 120-160 degrees on the track, if you get them over 170 degrees they will chunk, throw tread and blister. If tires are too hot they will get greasy, if they are not hot enough they will not provide the desired traction.

I strongly recommend that if you get serious going to the track that you invest in race tires on a good race wheel, which is stronger and lighter and will have the performance you desire. Your learning curve will quickly out pace even the best HP street tire on the track. AND, NO you can not buy one set of tires that will perform on the street and track.
Besides HP street tires are more expensive than race tires and offer less performance. Why burn them up on the tracK? They are OK for 1 or 2 initial sessions but after that you are better served with a race set up.

I recommend Hoosier or Kuhmo's in either DOT A or R compounds.
DOT A compounds (Autocross) heat up quickly (by second corner) and have a lower operating range from 110 - 140 degrees. Come in a single compound. These are graet for AutoX and will also perform great on the track with short duration heats, up to 25 minutes. Consider them like Indy qualifying tires.
DOT R Compounds (Race) need a few warm up laps and have a high operating range 170 - 200 degrees. Come in a single compound.

Note: Just because the tires are built to DOT Specs. does NOT mean they are street worthy. They are not.

R compound (non-DOT/true race tires) are the same but are strictly a Race compound and have just a slightly higher operating range 170-220 depending on compound (wider selection of compounds - up to 5). They are not built to DOT specs

[DennyM]

Nothing to add ... DJ covered it ... just wanted to welcome you to
You lucky dog you! ... with RA as your home track
Haven't seen that track since '71 ... but it's on my list, once I get free of the East Coast ...

[olf dog]

Thanks for the info everyone. I am very fortunate RA is only 45 minutes from home, I go up there every chance I get.