Hello,
I still have a hard time buying this.....Unless the tire actually expands when properly inflated, therefore changing the circumference, I don't understand.
The radius definately changes when the tire deflates, but, the circle becomes "untrue" at that point.
The ground covered is still the same, unless the tire actually expands when properly inflated.
There is a larger portion of the circumference making contact when the tire loses air, but still, the same amount of contact (per revolution) when the tire is full of air.
Jeese....I'm just a Plumber, don't hate me for thinking out loud....
Later now,
Clint