OK I need help again guys and gals.

I have a 66 Cuda with a 8.75 / 355 SBP rear end from a Duster and I have Cragar SS's
15 x7 in the rear and 15 x 6 in the front....both have approx 4 in backspacing I tried to stuff 255/60/15 under her.... not happening...then I tried 245/60/15 and they squeaked in but if I put a cooler in the car they hit the inner well on both quarters....( I centered my rear end before I did all this...most are off about a .25 on one side or the other). The largest tire I could fit in there SAFELY ( not touching anywhere even under load) was a 235/60/15 in the rear and a 215/60/15 in the front...... Newstalgia wheels has SBP cragar SS's for around $160 per which aint bad.... and there is a tire dealer on gratiot stree in Eastpointe Michigan that has the SBP Halibrand look alikes for a lil cheaper....