Which wheel travels furthest?

Clive George wrote:


What I still don't know is how that shape is achieved. It could be by
stretching/compressing the tyre material, or it could be by wrinkling
it. (he says showing lack of words!)

Will it, in some measure, be the material relaxing? The tyre must be
stretched to some extent by the air pressure within, so this stretching
could be relaxed in the contact patch. I've no idea of the numbers
involved, so don't know if that's enough to account for the deformation
needed.


I have a thermarest which I fold in half along its long axis before
rolling up. As I roll it up, I have to gather bunches of the mattress on
one side in order to keep it straight, since it doesn't stretch or
compress. That's what I mean by wrinkling, though it's an extreme case.

Thinking about it, it sounds unlikely that a tyre will be doing that, so
stretching/compression sounds about right. As the tyre enters/leaves the
contact patch, will it scrub?

It will depend on the tyre pressure, won't it? At a lower pressure the
tyre deforms more and there will also be less 'pre-stretching' due to
the internal pressure - so more scrub? That would certainly fit with
rolling resistance being higher at lower pressures. If the numbers fit
(as I've said, I've no idea what they are) it would also mean there was
an optimum pressure, above which there would be no further advantage
gained in reducing rolling resistance.

--
Andrew