[davelobi]

Originally Posted by RedDevil

By the way, there should be no difference in distance reported between new and worn tires, even though the new tires have a slightly larger circumference.

Amazing, no?

Consider this: A tire on a car is not a perfect circle. The contact patch is flattened out, and there the tread shrinks; the grooves narrow as the lugs get squeezed together.

By and large the distance a wheel travels with each rotation is the same as the length of the steel belts in the tire. The distance between the belts and the tread surface has no influence; again, the contact patch is flat.

Actually, if anything it is the other way round.
As my tires wear I see a very gradual reduction in the reported distance of my commute on the odometer. The same route that was 35.6 km when the tires were new now takes just 35.4 km.
I bet the belts have been stretched ever so slightly.

Worn tires slightly underreport the mileage.

I'm not convinced. Take your examples to a little more extreme to magnify the effects. Use a much larger tire and see how few revolutions it takes to any stated distance compared to the smaller one. I don't care how large the footprint is, bigger going further per rev.