tyre pressures
Discussion
Ash GTO 3R said:
after they have been warmed up.
Cold pressures. If you are really worried then take an IR thermometer with you and check the temp across the tyre after a few laps. Too hot in middle, lower pressure. To hot on the outside, raise pressure.
I've always managed to keep tyre wear pretty much even by doing that.
J
You sure they are cold pressures? I've always done my tyre pressures once the tyres were at running temp. No point getting the pressure right for when they are at environment temp because thats not what they run at when in use and theres too much variance as to what the pressure change will be since environment temp swings so much.
DanH said:
You sure they are cold pressures? I've always done my tyre pressures once the tyres were at running temp. No point getting the pressure right for when they are at environment temp because thats not what they run at when in use and theres too much variance as to what the pressure change will be since environment temp swings so much.
Dan, if you take the reading hot then this will be a temporary reading (as it'll change when the tyre cools down) and you'll end up with far too much air if you inflate from this point - so I always read at cold - eg: after the car has been parked at the track for a while after arriving.
Apart from the pressures, the main thing to ensure, is that the tyre pressures are matched.
IMHO it's a *cold* reading.
The *right* pressure when on track after you have just come in (as per the therometer method) is around 19 front, 32 rear, but that changes wildly depending on the actual temperature of the tyre.
The only real way I've found is to wait until the tyre isn't "warm" to the touch and then check it.
J
The *right* pressure when on track after you have just come in (as per the therometer method) is around 19 front, 32 rear, but that changes wildly depending on the actual temperature of the tyre.
The only real way I've found is to wait until the tyre isn't "warm" to the touch and then check it.
J
Well I admit I'm just going by my Elise manual that said the tyres had to have some warmth in them to check temps. I assume that running temps are going to be a lot more consistent than atmospheric temp.
Hopefully the factory can settle this one
p.s. Rob you won't have too much air if you do it when up at running temp (be it track or road running temp) as the air expands as it gets hot. If anything it would be too little.
Justin has the answer. Whatever the pressure in the tyres, whether first measured cold or hot or "coolish after they were once hot", if the pyro measurements show uneven temps then adjust the pressures accordingly.
Remember there is no fixed answer. Pressures for a wet day in winter are very different for a hot dry day in the heat of the summer. In the later there will be so much more heat generated (and retained) in the tyre that you'll probably end up letting air out to control the pressures. With the same left cold overnight tyre pressure the summers day tyre will probably have 5-10 psi more in it after a few laps than the winter tyre.
Remember there is no fixed answer. Pressures for a wet day in winter are very different for a hot dry day in the heat of the summer. In the later there will be so much more heat generated (and retained) in the tyre that you'll probably end up letting air out to control the pressures. With the same left cold overnight tyre pressure the summers day tyre will probably have 5-10 psi more in it after a few laps than the winter tyre.
paulcundy said:
Justin has the answer. Whatever the pressure in the tyres, whether first measured cold or hot or "coolish after they were once hot", if the pyro measurements show uneven temps then adjust the pressures accordingly.
Remember there is no fixed answer. Pressures for a wet day in winter are very different for a hot dry day in the heat of the summer. In the later there will be so much more heat generated (and retained) in the tyre that you'll probably end up letting air out to control the pressures. With the same left cold overnight tyre pressure the summers day tyre will probably have 5-10 psi more in it after a few laps than the winter tyre.
Sorry - I shouldn't have used the word pressures, of course the "pressures" will be the same but the amount of air having to be pumped in or out to maintain the "pressure" will be different on the different days.
I'll stop trying to be helpfull!
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