My 245/45's look perfect on cobra 9" rims. I have a picture but don't know how to post it (fairly new to this stuff). However I am changing to 18's 245 up front 275 or 295 if they will fit out back(new brakes comming).
I've never put any 18's on a fox body before but I have seen them. 295/30/18 is a huge tire though.....it would fit on the wheel (tight fit though!) but I'm guessing you would have rubbing problems on the rear, quadshocks for sure, also tailpipes if it's an LX. I'm assuming you mean just for the rear because there's no way that size tire would fit in the front.