what the guys are not saying is that the tire needs to be sized properly so it does not rub on the spring perch of the stock strut - that spring perch is your limiting factor. (laegion did kind of mention this)
yes, you can put a bigger wheel on, as long as the tires are sized to clear.
Alternatively, you can easily put early Forester struts on which will slightly increase the spring perch clearance area allowing for a larger tire. This is what I did on my 95 Legacy...and I loved it!