It does depend on the tire, but in general there is a "sweet spot"
which provides the maximum grip. Below that pressure, the tire is too
soft and tends to roll over onto the side of the tread and/or lift the
inner edge. Above that pressure, the tread bulges a bit and reduces
the area of contact between the tire and the ground.
There is also a secondary effect described by Andy Hollis, wherein
higher pressures increase the effective spring rate of the tire. If
the effective spring rate of the tire is comparable or softer than the
spring rate of the suspension, then changing the spring rate of the
tire can have a significant effect.
At your next event, ask someone to show you how to use chalk or shoe
polish to judge your inflation pressure.
On Fri, Jul 06, 2001 at 12:18:44PM -0700, Lawrence Lane wrote:
> I was told at the track by someone I met that the more air pressure is given,
> the tire will have more traction. I thought this sounded weird, but I thought
> I'd try it out. So, I inflated my 18"s to 35 in the front and 40 in the rear
> to decrease oversteer. I'm not sure if it was the car or not, but I
> experience a huge amount of oversteer. What is the general rule about this?
>
> Thanks
>
> Larry
> FD3S
--
john@idsfa.net John Stimson
http://www.idsfa.net/~john/ HMC Physics '94
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