Track Tyre Pressures

[MadUsa1]

going to the track this evening with the 200.

ambient temp will be about 25 degrees.

I'm on Toyo R888's - what tyre pressures should I be running? Do I need to mess about with them between sessions or can I just set them to the factory 2.4 and be done with it?

 

[ForceIndia]

Direct from Toyo:


The R888 has a semi race construction (very stiff) and a race tread compound. The optimum tread temperature range is between 85C and 95C measured using a probe type pyrometer, and ideally a maximum difference across the tread of 9C. The maximum hot pressure we recommend is 40psi. Camber angles up to 5 degrees are permissible but the final setting will depend on tread temperatures. It is advisable to have as much positive castor as practical as castor induces a beneficial camber change during cornering. I recommend that the tyres be put through 2 heat cycles before hard use.


The pressures you use will initially depend on the weight of the car, too little pressure on a heavy car can lead to over deflection of the tyre and subsequent failure.

Below are some basic settings:

VEHICLE WEIGHT COLD PRESSURE HOT PRESSURE
Very Light < 800kg 17 - 22 psi 22 - 29 psi
Light 800kg - 1000kg 20 - 26 psi 24 - 32 psi
Heavy 1000kg - 1400kg 23 - 27 psi 28 - 40 psi
Very Heavy > 1400kg 27 - 35 psi 37 - 40 psi


As a tyre gets hotter the pressure increases, this is due to the moisture in the air. The cold pressure you set to achieve a desired hot pressure will depend on the conditions on the day i.e. ambient and track temperature, wet or dry. If the day/track is cold you will need to start with a higher cold pressure as the tyre will not get as hot therefore the pressure increase will not be so great.
Hot pressures must be balanced side to side. Once the tyres have cooled you will find that you will have a difference in pressure side to side, if you have been racing on a right hand track you will find the offside pressures will usually be higher than the nearside. __________________

 

[MadUsa1]

ok, so start with a cold pressure of around 25 psi and monitor between / during sessions to ensure it never gets above 40 psi hot.

sound reasonable?

 

[Fred@BTM]

you'll have to c**k about with it lots, depends on vehicle weight etc etc etc, aim for 30spi all round HOT as a starting point and adjust from there, so set them at rear 27 fronts 25 cold and see how you go

 

[MadUsa1]

thanks for the advice, will see how it goes tonight!

 

[Soot1e]

Does the above guide to track pressures apply to other trackday tyres as well? I have Advans on my Cup.

 

[ForceIndia]

Specifically to the r888's. With others just play about with them, see what works best!

 

[Soot1e]

Cheers Mr. Bear. Yes I've been doing that, as Fred says, started at 27psi all round, which seemed soft for a couple of laps then the next tracday started at 30 but seemed too hard and bouncy. As Im on standard springs it will more likely be them that caused the problem so a set of Eibach Pros will be fitted soon.

 

[jenic]

This has been posted before but I have forgot

How should front and rears be adjusted in relation to over/understeer?

 

[Moose4624]

Nitrogen FTW

 

[Dangerous_dave]

Nitrogen FTW

Kwik fit too no doubt lol