P235-70R-15 fitment

OE cop rims are 15x7 and 4.25" backspace. Wheel Vintiques offers a few different widths and backspacing options.

The 225/60/15's will be fine up front, maybe a minor adjustment or two, maxing out adjustments etc. Assuming you're running 73+ Mopar disks.

In the back 255/60/15's will be easy on cop rims. 275's fit in the wheel wells just fine out back on a duster. Problem is that 275/60/15's shouldn't be on anything narrower than a 15x7.5". Yeah they'll squeeze on there but it's out of spec for OE cop rims anyway.

Other thing about 275's is the backspacing might be a little light, if it's an a-body 8 3/4 with BBP axles you'd want a little more. The OE cop rims have a +6 offset, +12 would be better. 15x8 with a 5" backspace would be better. But if your ride height isn't that low it probably won't be an issue.