Toolmanmike.....I have 8"X15" cop wheels on my '65 Valiant (all 4 corners) with 215-60 tires on the rear. With careful attention to back spacing you should be able to fit a set of 235-60 tires on the back. 225-60 for sure. I think a 7" wheel with 4 1/2" back spacing is where I need to be, the 8" wheel pushes the sidewall bulge out a tad too far. My fronts have 195-60 tires on them but that is what was there when I bought the cqr.
Higgs.....what is your tire size, especially the diameter? Did you use lowering blocks to drop the rear? If so, ain't adjusting the rear brakes fun?
Bob