On Thu, 28 Jun 2018 16:20:07 +0100, "dennis@home"
wrote:

snip

Rubbish.

And most of the people (worth considering) agree.

The tread on the tyre and the side walls deform as the tyre rotates
changing the actual circumference.

Yup.

The change depends on the contact length which changes with pressure,
load, tread pattern, rubber compound, type of belts, etc.

Yup.

Even a steel tyre like those on trains deforms as it rotates.

Ere, tell Turnip and his goblin assistant (Streater) that a part of a
train goes backward as the train goes forward and watch their tiny
brains explode!

Cheers, T i m