(65 Barracuda)What is the largest 15" rear tire I can run without tubs/rubbing?

Hey guys, I have looked back through some old posts and can't find any that deal directly with this issue . What is the largest size rear tire on a 15 inch rim but I can run without having to tub the wheels or have issues with rubbing ? I am currently running 14 inch 225 7014's and I want to go with the 15 inch five on 4 inch rims and want to know what size rims to get an what's the biggest tire I can run I'm looking for some height and some width. This should improve my rpm cruising speed. I was going to guess that I could run a 245 or 255 70 15 but don't know whether I should put it on 15 x7" rims were 15 x 8" rims?

Anyone that has tried it I would really appreciate some advice..,


Thx
I have run 245/60/15s on 15X7 wheels with a 4.5" backspace on a few 65 and 66 Barracudas with out any issues, 255/60/15s were just a bit to wide and would rub if the ride height was low in the rear.