[ultra]

I've asked this very same questions before on this forum and was told that it'd probably depend on circuit layout. In some cases more speed from a lighter & narrower rim & tire combo might outweigh the extra grip of a wider combo. Or maybe not.

Consensus was around 8 or 9 inch rims and up to a 245 width R comp max, or less rubber width if you aren't heating up a 245 properly.

I barely roast 225 R comps on my track - vague curling around the trad blocks but no crazy wear or melting.

Autocrossing may be different again.