Re: Hydroplaning

[Bob <mx@snet.net>]

Graydon D. Stuckey wrote:

> On Wed, 25 Nov 1998, Geoff Jenkins wrote:
>
> > Been thinking about this... I agree in re: the effect of pressure, but _how_
> > do you separate pressure from area? Assuming vehicle mass is identical, as
> > you lower the pressure, surely don't you soften and flatten the tire, so
> > that the force downwards remains constant?
>
> I tihnk that the pressure is merely the factor that produces the feature
> that improves hydroplaning.   Its the hardness of the tire that affects
> hydroplaning.  Sinceair is compressible and water is not, you need alot
> of pressure to reduce how much the air compresses when it hits water.  If
> it compresses very little (extremely high air pressure) then the shape of
> the tire stays relatively constant, and then it becomes a fight for
> space.

But a tire doesnt keep its shape with different pressures. When you get to lower
pressures,  the center of the tire tends to lose contact pressure with the road.
Just the inverse with higher pressures, the center will wear more than the
outsides.

Bob