RE: Contact patches

["Paul Wilson" <pwilson@ma.ultranet.com>]

> Sure it does, Dave.  FE, put a 255/50 15 @ 32psi on a 15X6 stock
> audi turbo
> quattro coupe wheel.  What happens to the tread near the sidewall?  What
> about overall diameter?  Put the 255/50 15 @ 32psi on a 15x9 Urq
> racing rim.
> Any difference in contact patch?  Elementary to the proper sizing of rim
> width to tyre width.  We could speak of the contact patch of a
> 245/40 17 on a
> 17X7 in RS2 wheel too I suppose. ;)

With a radial tire, theoretically speaking and give a reasonable rim width,
the tire contact patch should not change.  That's part of the point of
radial tires.  If you take a 255/50 tire and put it on a 6" wide rim, yes
the contact patch will probably be effected.  A 255/50 on a 6" rim is
unreasonable.  If you compare a 225/50 on a 7" vs. an 8" rim, there won't be
much of a difference.  What can change slightly is the outside diameter of
the wheel/tire combination.

> Try www.thetirerack.com.  They do a fine job of explaining the elementary
> wheel and tyre questions.  Plus sizing is in there for you too.
>
> Scott Justusson
>