Steve is right. Rotational moment of inertia relates to how much torque is required for rotational acceleration. A pair of wheels can weigh the same but one will have higher rotational inertia making it swallow more torque to accelerate in rotation. The maximum impact of rotational inertia comes at the maximum radius of the part. Rubber is heavy and is at the maximum radius so tire weight affects rotational moment of inertia the most.

For those interested: J=(.5*Pi*R^4)

Where:

- J is rotational moment of inertia
- Pi is 3.14159
- R is radius from rotational axis to point of mass

It is obvious that the distance (Diameter and width of tire in this case) affects torque requirement to accelerate to the 4th power.