Track tyre pressures - Silverstone GP track?
06-07-2007, 01:02 AM
#16
Burning Brakes
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There is more going on with your tyres than you realise. The problem you report is (almost certianly) not a pressure one but due to the fact you are running road tyres. As the tread heats up, it begins to move around on the carcass and you can actually feel the tread blocks moving! It is very disconcerting and makes the car feel more loose than it really is. Obviously, the amount of this depends how much wear there is on the tyres!
The real issue with this is that it starts weight transference. You are never certain whether this will lead to loss of traction or just some rolling on the tread so the car feels more unpredicatable.
I am unable to do more than 8-10 minutes on street tyres without this being a real issue. The answer is to get a track focused tyre.
The real issue with this is that it starts weight transference. You are never certain whether this will lead to loss of traction or just some rolling on the tread so the car feels more unpredicatable.
I am unable to do more than 8-10 minutes on street tyres without this being a real issue. The answer is to get a track focused tyre.
06-07-2007, 05:02 AM
#17
Racer
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Your probably right Simon, it was really disconcerting and I was beginning to wonder if it was a flat (but it wasn't that bad) or my imagination, so I backed off and went back to the pits. All the wheels were still there and the pressures were still the same.
06-07-2007, 10:25 AM
#18
Burning Brakes
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Originally Posted by SimonExtreme
Tony
I have heard these stories about not running on low pressure but I cannot see how that works. It certainly doesn't work when racing. Or the supersprints I do. My fastest times are when the tyres are hot but the pressure is right. If I start at the right pressure, it will be too high when up to temperature.
Or lets look at trackdays. How are you meant to drive? Go out at normal pressure - come in and reduce pressure after 2-3 laps - go out again for rest of session - inflate tyres when they cool between sessions and repeat! I have never seen anybody do that!
I am sure that theory says never run under inflated but I haven't heard of any significant problems from running the way that has been suggested.
I have heard these stories about not running on low pressure but I cannot see how that works. It certainly doesn't work when racing. Or the supersprints I do. My fastest times are when the tyres are hot but the pressure is right. If I start at the right pressure, it will be too high when up to temperature.
Or lets look at trackdays. How are you meant to drive? Go out at normal pressure - come in and reduce pressure after 2-3 laps - go out again for rest of session - inflate tyres when they cool between sessions and repeat! I have never seen anybody do that!
I am sure that theory says never run under inflated but I haven't heard of any significant problems from running the way that has been suggested.
Simon, as you say in sprints and most races you start on "hot" tyres so the pressure is correct or often start slightly low so that the correct pressure is atained in the race itself. Track/race tyres are different from road tyres in any case.
On trackdays typicaly I'll take the approach that if my last trackday was recent and the tyre pressure was OK at that date, then I'll start with whatever pressure is in the tyres. I always warm up on my first session anyway ( I usually do open pit days )
As a novice new to a circuit it's possible that it could take a few sessions before you're driving hard so starting low pressure might mean running low as you're not generating enough heat.
Road tyres heat up very quickly though if you drive hard in the dry so pressures rise very fast, then they start to melt and bits chunk off
