Ed,
Here's the specs on the wheels I have. My bad, my TSWs are ET20, but fitment is as posted.
M5 Reps: 19x8.5 ET35 front, 19x9.5 ET35 rear
TSW Mugello: 19x8 ET20 front, 19x9.5 ET20 rear.
These specs have 100% been on my car. The M5 reps are more flush than the M Sprt OEM, but my TSWs are damn flush and almost sticks out a few mm with the sidewalls of the rim protector.
So 10s in the rears will be sticking out beyond the fender.
TSW
M5 Reps
OEM