Not to fan the spark of a flame but you are both right.
Long reason: It is all about the size and shape of the contact patch.
If this bit fails, NOTHING else matters. The confusion usually comes
when someone introduces the "coefficient of friction" -- which is
independent of area. The point that is usually missed is that the simple
friction model is too simple. One must also take into account the
deformation of the rubber into the rugosity of the road surface. This
causes the SHAPE of the contact patch to influence the tire's traction
preferentially according to the direction of the forces.
Short lesson: Wider tires make for better cornering if the surface is
paved. Narrow tires are better for cases such as ice and snow.
Empirical evidence: Wide tires on Formula 1 cars. Narrow tires on
World Rally Series cars on the Alpine Run.
I have a nice little image of the traction circle if anyone wants a copy.
It graphically explains why tires can't corner AND accelerate at the same
time. :-) Just drop me a line and I'll send it to you. It's just a JPG of
a drawing.
Rick
Ajhsys@aol.com wrote:
> In a message dated 10/10/00 9:07:05 PM Eastern Daylight Time, Emjaxfl@aol.com
> writes:
>
> << Many years ago there was an excellent article on this topic. The wider
> tire
> with the lower aspect ratio actually has the same size footprint as the
> narrow tire with a taller aspect ratio. Something about the Law of
> Archemedes
> and equilibrium of the forces involved. The key point is the shape of the
> footprint. The wider tire will have a wider footprint and that will be able
> to generate a larger slip angle before the limit of adhesion is reached.
> Therefore, cornering forces will be greater than otherwise.
>
> Should I put on my flame suit now? >>
>
> - - - - - - - - - - - - -
>
> Nope. You are right. As long as the tire pressure is the same and the
> sidewall is the same stiffness...the footprint will have the same area no
> matter what width/aspect ratio.
>
> This thread got pretty heated on the list about a year ago.
>
> Allen Hefner
> SCCA Philly Region Rally Steward
> '77 Midget
> '92 Mitsubishi Expo LRV Sport
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