Moment of inertia is not a standard formula that can be applied to all wheels. because wheels have different designs this can change the way the mass is distributed, thus a different moment of inertia formulation.wmiller19 said:
Considering that the moment of inertia is what opposes rotational motion and force, this can have an effect on accelerations.
i.e. a wheel 3lbs lighter could have a higher moment of inertia by design than that of the wheel 3lbs heavier.
Now for my little rant:
Why someone wants to put on 40lbs bling bling 20"s on a 4 banger compact is beyond me. There is no better way to make you car slower than adding those rims.
As for me, the most important factors are: Construction > Weight > Price.
Sure there is no point driving on 8 lbs forged magnesium alloy rims on the street, but they're good for track.