Originally Posted by lucid
Despite weighing almost the same, the 19" rims will have slightly more rotational inertia than the 18" rims as the majority of the rim mass is distributed further away from the rotation axis (by 0.5" in this case). But that effect would be so small that one cannot feel it.
that's exactly right, theoretically (not taking into account distribution of mass throughout the wheel, which can vary) a 15" rim (notwithstanding the brake clearance issues!) with a tire size to have the overal wheel size of these 19" and 18" setups and of identical weight, would have a more noticeable difference in rotational inertia, as the mass is concentrated around the hub....most drag strip cars have pretty small rim sizes, im thinking this plays a factor in that decision!