The other fun aspect is how low you run your mr2. Carmikey shows a modestly low mr2, the lower you go the more accurate you need to be with offset/width/size/tyre.
In saying that rims can be shaved a few mm, guards can be rolled, ride height can be raised on coilovers.
You didn't mention the fronts, and that's the usual challenge with mr2s in getting rims with the right offset and also importantly is the rim width staggered, so 9s on the rear, then 8s on the front (similarity offset as per examples listed). The wheel tracking is based on offset and width impacts your mr2s handling.