I have a 79 El Camino with a 12 bolt out of a 68-72 Chevelle. Right now its got a 8.5 inch wide wheel with 5" of backspacing.

I am wondering if anyone knows if a 245/55/18 will fit on a 10" wheel under this?

I measured the distance from the frame to the fender lip and its 11 7/8 total. I do have plenty of fender lip that I could curl or trim to help squeeze it in if needed.

Any advice would be appreciated, thanks in advance.