From what I've seen given proper offset
265/30 no rub
275/30 no rub
Anything up to 305/30 fits, even lowered on H&R or Eibachs. Askiles has 305/30-19 on the rear of his car with no rub.
Again this is just what I've seen for myself, your mileage may vary.
With my Volk G2s I'm doing 275/30 front and 295/30 rear in order to stay at a 20mm stagger and keep the speedometer pretty close to being accurate.