@Benator I'm not sure I understand why should vesuvius stop making great work, just because you have older computer?
You probably missed this but vesuvius and Hega made something revolutionary, tyres switching colors live, is for some reason enough to use them, but again not necessary.
Rim shape is not at all that heavy as one may think for being 3d rim (someone can check poly count, I couldn't care less), textures may be too high I dont know, but what's stopping you from downsizing them as you said you do anyway.
It would be nicer if you would explain how authors can help you out and maybe make tyres even better.
And vesuvius said numerous times that there will be 2d version of his and Hegas work. Maybe that can solve your troubles (in gaming department that is).
Besides high PO, does it really depend on sole tyres or could it be 40 000 poly cars?