Track day tyre pressures

[craiginuk]

Tried the search function but could not find anything on this - althogh am sure there was a thread about it.

What would a good starting point be for tyre pressures for Bedford. 16" rims, I normally run 32 psi all round on road. Was thinking of dropping to 30 cold before the short drive from hotel to track. Any suggestions?

 

[944 man]

The answer is an accurate gauge, a pump and maybe an I/R thermometer. You arent far out to begin with, but pressures are more of a preference than a science in this circumstance.

 

[Copperman05]

Advice from Chris at Center Gravity was to run at road pressures (36psi) and then adjust. Danger being that if you start at lowered pressures the car can understeer before tyres get a chance to warm up. At 30psi I don't think you would have an issue but perhaps better to take or borrow a tyre pressure gauge and reduce to 28-29psi hot, after a few laps, depending on tyre.

Apparently many off circuit excursions are due to drivers not putting air back into the tyres after the lunch break and going back on track with cold, low pressured tyres.


Edd


Edited to add:

I just called CG to confirm, because everyone will be running on different setups, tyres, driving styles then its difficult to give pressures most suitable for all. What he did suggest was to run at 36 psi, measure after few laps and then reduce to keep at the 36psi mark and to repeat this as the tyres heat up. Without a pyrometer its difficult to know what temps the tyres are at to set pressures accordingly.

 

[Masher]

I agree with the mind set to warm the tyres then drop back to typical road pressures. I have often found this means taking 6 to 8psi out of the tyres on a dry day.

For interest, my 944 is new to me and it runs on 17" 911 wheels (225/40/17 front and 255/50/17 rear from memory) - what is the normal road pressures I should look to have? 32psi all round as mentioned above?

Cheers
Mick

 

[944Turbo]

32 is what I run my road tyres at, 36 wears the centres 17" 225 or 215 fronts (dependant on the set) and 255 rears

 

[Masher]

ORIGINAL: 944Turbo

32 is what I run my road tyres at, 36 wears the centres 17" 225 or 215 fronts (dependant on the set) and 255 rears

Many thanks
Mick

 

[edh]

I aim for low 30's hot. maybe 32 for ad08 on my car. Start at normal road pressures and adjust down, keep checking and adjusting until things stabilise. I've seen road tyres shoot up above 40 in a few laps.

if your tyres are squealing and theres no grip then you know they are too high (or you are trying to turn in way too fast...)

track tyres can run a few psi less than road tyres.

if there are signs your tyres are rolling onto the sidewalls then they are too low.

you can also adjust one axle by a couple of psi to change the balance of the car - if you are understeering then take a bit from the front. (of course there may be other reasons for understeer, like driving style...[])

in my opinion, 944's are very easy on tyres compared to many other cars.