Logan
June 27th, 2003, 11:38 AM
I think this will be a good thread for anyone interested in this.
This information is for FRONT WHEEL DRIVE CARS ONLY.
When competing with your car in autox/solo events, the common practice is to increase tire pressures.
Why?
When competing on these tight courses, you are transfering load to and from your tires quicker than normal street driving.
The most basic reason for increasing pressure is to prevent the tire from "rolling" in a corner. If the tire rolls, you are then using the side of the tire for traction, instead of the tread. In worse case scenarios, you could roll the tire off the rim.
Nobody wants that!
There is an optimal setting for each tire, depending on drive/course/weather conditions.
A good idea is to increase front tire pressures to approx. 40lbs. This will prevent rolling while still offering good traction.
You can then fine tune your pressures with a few different methods.
The best way is to use a Pyrometer. This device measures the temperature of the tread. Use one IMMEDIATELY following your run. Even temperature across the tire indicates perfect tire pressure, as you are using ALL of the tread for grip. Higher temps in the middle means you are using the middle of the tread more than the outside, you do not have optimal grip. Higher temp on the outside indicates you are using the outside more than the middle, again, you do not have optimal grip.
What if you don't have a pyrometer? Use some shoe polish on the edges of the tire where the tread runs onto the side.
If after a run all the shoe polish has rubbed off the side, your pressure is too low and the tire is rolling.
If after a run ALL the shoe polish is still on, the pressure is too high. Ideally you will have shoe polish rubbed off the edge just a bit.
Notice how I haven't talked about rear tires?
You can use the pressure of the rear tires to change the handling of the car.
By changing the pressure of the tire (up or down) you are changing how much of the tread is in contact with the surface you are on. If you want the back to be loose, add some pressure to the tire. This will overinflate the tire, pushing the middle of the tread out more than the edges, now you have less tread in contact with the surface making your car loose in the back.
If you find your car tough to control in corners, try letting some pressure OUT of the rear tires, this will allow more of the tread to be in contact with the surface, now offering more grip and making the back of the car "stickier".
Tire pressure adjustments should be made in 2lb increments.
OK, I'm now waiting for people to argue with me on the rear pressure theories!
GO!
This information is for FRONT WHEEL DRIVE CARS ONLY.
When competing with your car in autox/solo events, the common practice is to increase tire pressures.
Why?
When competing on these tight courses, you are transfering load to and from your tires quicker than normal street driving.
The most basic reason for increasing pressure is to prevent the tire from "rolling" in a corner. If the tire rolls, you are then using the side of the tire for traction, instead of the tread. In worse case scenarios, you could roll the tire off the rim.
Nobody wants that!
There is an optimal setting for each tire, depending on drive/course/weather conditions.
A good idea is to increase front tire pressures to approx. 40lbs. This will prevent rolling while still offering good traction.
You can then fine tune your pressures with a few different methods.
The best way is to use a Pyrometer. This device measures the temperature of the tread. Use one IMMEDIATELY following your run. Even temperature across the tire indicates perfect tire pressure, as you are using ALL of the tread for grip. Higher temps in the middle means you are using the middle of the tread more than the outside, you do not have optimal grip. Higher temp on the outside indicates you are using the outside more than the middle, again, you do not have optimal grip.
What if you don't have a pyrometer? Use some shoe polish on the edges of the tire where the tread runs onto the side.
If after a run all the shoe polish has rubbed off the side, your pressure is too low and the tire is rolling.
If after a run ALL the shoe polish is still on, the pressure is too high. Ideally you will have shoe polish rubbed off the edge just a bit.
Notice how I haven't talked about rear tires?
You can use the pressure of the rear tires to change the handling of the car.
By changing the pressure of the tire (up or down) you are changing how much of the tread is in contact with the surface you are on. If you want the back to be loose, add some pressure to the tire. This will overinflate the tire, pushing the middle of the tread out more than the edges, now you have less tread in contact with the surface making your car loose in the back.
If you find your car tough to control in corners, try letting some pressure OUT of the rear tires, this will allow more of the tread to be in contact with the surface, now offering more grip and making the back of the car "stickier".
Tire pressure adjustments should be made in 2lb increments.
OK, I'm now waiting for people to argue with me on the rear pressure theories!
GO!