Tried some friends wheels on today, they fit absolutely perfect IMO.
Fronts: 18x9.5 +12 245 40r18
Rear: 18x10.5 +15 275 40r18
The fronts fit perfect with a little camber, sit fender to lip almost and compress up into the fender nicely. Rears could be a tiny bit wider and still be fine.
30mm wide front fenders 50mm rears.