Running on a "regular" rolling road is subject to all sorts of external influences for the power @wheels figure. Wheel size will have an effect (think of it as gearing). Whether you'd ever notice/record the effect with all the other inconsistencies is very arguable especially given the max difference in rolling radius you can actually achieve in practice on your Supra with those big brakes. Tyre pressure will have an effect, tyre grip will have an effect etc etc. Wheel weight...I guess the greater the wheel weight, the greater the load you are "putting on the engine" which (especially on turbo cars) could have a positive effect on making the bottom end torque a little better.
Almost. This was many many years ago on small capacity race prepped NA engines.....but rather than wheel size I was experimenting with final drive ratios. I've never really given the wheel weight question any thought to be honest.
Everybody knocks Thor as their numbers are high but if you want back to back consistency between visits then an engine dyno would be first choice, a hub dyno (like Thor) would be second, then after that you're into "rolling roads" and my first choice there might well be a Mustang Dyno and then a Dyno Dynamics setup like SRR.