205/40/17 is the exact size you'd want on the front for an 8j et20 on an e36
215/45/17 for the rear should be perfect on a standard arch (it fits a 9j et26 with no issues), it'll look nice without looking over the top too which is what you'd want.

You'll need to be fairly low to pull it off though, but I assume that's the case.

We'll need pictures once fitted