I've heard of people having issues with the axles bottoming out, but I haven't encountered it. I drove to work this morning in my XT6 with '92 FWD Legacy front knuckles and axles in it.
Hmm, it was my understanding it wouldn't fit the axle. What tie rod end do you use? I know the ea82 tie rods are not the appropriate size.
EA81 rod ends are the ticket, same threads/taper, but shorter overall length.
I, too, had rubbing issues with 225 on WRX wheels (225/60r16, IIRC), both on the trailing arm and the spring perch (Miata shocks, at the time). But I had plenty of clearance with the fender. And my 215s on my 17x8+48 Rotas had plenty of clearance with the arm, and was crazy tight against the body (and still rubbed against the frame rail in the front while turning).
So I think a 225 could be done with the right offset wheel. But anything beyond that would require fairly significant modification. And you can get a lot of grip out of a 225!