Tire Pressure for Track Work

[hoss4659]

I have been thinking about entering the local PCA region's DE event at the Inde Motorsports track (near Wilcox, AZ). The car is a 1988 Carerra 3.2 running on Conti DWS Extreme Contact tires, 205/55-16 and 225/50-16 on 7 & 8 X 16 wheels. I have been using the factory 29F, 36R pressures for the street. Should I keep these pressures for high speed track work? Or should I bump the pressures up a couple of PSI? This will be in mid-November and with good weather we will probably see mid day temps in the mid 70's to the low 80's from lows in the 60's at the start of the day. Less pleasant weather might drop the temps 10 to 15 degrees.

[Bill Verburg]

Originally Posted by hoss4659

I have been thinking about entering the local PCA region's DE event at the Inde Motorsports track (near Wilcox, AZ). The car is a 1988 Carerra 3.2 running on Conti DWS Extreme Contact tires, 205/55-16 and 225/50-16 on 7 & 8 X 16 wheels. I have been using the factory 29F, 36R pressures for the street. Should I keep these pressures for high speed track work? Or should I bump the pressures up a couple of PSI? This will be in mid-November and with good weather we will probably see mid day temps in the mid 70's to the low 80's from lows in the 60's at the start of the day. Less pleasant weather might drop the temps 10 to 15 degrees.

You'll have to experiment w/ cold pressures to start w/ but you'll probably want to end up w/ something like 34/35 hot.

Where you start cold depends on ambient temp and how much the pressure builds w/ use on the track, If its a 70F day maybe try starting at 29/30 cold then check after 4-5 laps

[aston@ultrasw.c]

You should go. Great track, great instructors!

[Quicksilver]

The only way to set tire pressure is using a skidpad or at least a constant radius corner where you can see what it is doing in a steady state corner.

A tire pyrometer will seriously shorten your time experimenting.

- Get tires up to temperature and record the temp and pressures.
- Change the pressure only on one end of the car at a time and make notes on how it changes the grip on that end compared to the other end.
- Switch ends and do the same to maximize that end's grip.

Once you figure out which end has the least grip when it is set for best grip you can then back off the other end to balance the car.

[BFT3.2]

Exactly what Bill said. You'll also find whichever way the track turns the most, your outside (especially rear) tire(s) will get hotter. Check your pressure as soon as you get off track and you'll prob find those outsides at a higher PSI and you'll have to bleed them more.

With a "lightened" 2600 lb G50 with Bridgestone RE-11, I've had very good results running at 33/36 hot.

[911 Rod]

Is this your first track event? If so just make sure there is air in them.