245/60/15's on 15X8 rims

On your Coronet? They can handle 15x8's easy and the 255's work well on 8" wide wheels/ I have 255's on 7" wide and they work ok. View attachment 1715147175 View attachment 1715147177
Not sure who sees what when I send this. I'm upgrading pretty much everything on '71 Swinger. Wheels next on the docket. Went from 14 X 4 BP wheels to now (needs to be 15" wheels) because if disc brake upgrades. I'm getting regular ole' steel rims for now $$$$$ but would like to put a wider if not the widest tire in the rear. New 8 3/4 rear coming with wilwood disc conversion on rear. Front is the package from Performance Online. The ? is how wide should the 15 X ?? steel rim be? Going with the 15 X5 or 15X6 for a skinnier tire look in front. How wide rim?, How large Backspacing?, for a good wide tire on the rear. And..... Any Boneyard leads since this is not my final answer? aka when I hit Lottery will have customs done....