Originally posted by tboner:
One more thought on this. If the wheel is lighter, and the wheel/tire combination is lighter, and the circumference is the same or less, then how is the moment of inertia greater?
It is still possible for a wheel/tire combo to have this combination while still possessing a greater moment of inertia. The moment of inertia is a measure of the mass distribution of an object about the center of a rotational axis. Since most wheels are symmetric about their rotational axis, the moment of inertia is proportionate to the mass of the wheel/tire and the square of the radius that defines the average distribution of the mass from the wheel center. So if this radius from the lighter/smaller-diameter tire/wheel combo was greater than that of the heavier/larger-diameter wheel, there is a possibility that that factor could outweigh the mass difference between the wheels, and produce a greater inertia.
