This, on Mike Sandford's suggestion, is the new arena for him and Mark to continue their fascinating discussion of what happens as tires roll.
For foregoing discussion see the discussion "Track Portion of a Road Course."
Mark's discovered article made me aware of the role of shear in the contact area, which I'd not considered, nor do I think I have the technical horsepower to analyze.
The temporary reduction of circumference, as the tire rolls, within the contact area makes me wonder - should we be thinking of "effective circumference" rather than "effective radius" when we consider change of constant with tire pressure?
I haven't done the calculation yet, but as the axle is loaded toward the ground, the contact area grows. There is a relation between the axle-to-ground distance and the length of the contact area. The effective circumference of the tire could, on first approximation, be the length of the undeformed portion of the tire plus the length of the contact area.
This effective circumference would act on our constant in the same direction as would "effective radius."
The above analysis needs work, but it's a start - or rather a continuation.
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