If they are 17x8s you can use 245/45s. I am running 99GT wheels with 245/45 tires on my lowered 85 with SN95 fronts and Mark VII rears. There is no more rubbing than I had with 10 Holes and 225/60s. Just a little bit on front of the inner fender lining.
i have 245/45 on the 17x9 cobras on my 88 and they touch the front sway bar under a complete lock to lock turn but as i said in another post when i replaced my 4cyl rack with a gt rack it may have not come with the rack limiters installed in it.you should go with 255/40 and 275/40 it really fills up the tire well nicely as i've seen on other stangs.