Need help sizing Coys on a '72 stepper

[trichmond60]

Hey All,

I've spent hours searching around to find a definitive answer on what fits and what hits on a lowered stepside. I have a '72 with a 4.5" drop in the front and 6" in the rear. I'm looking at some 18" Coys C5 rims and I'm unsure if there's a defined limit as to how tall and how wide one can go with a tire before rubbing.

Does anyone have experience running a similar setup? Rim width? Backspace? I'd like to shoot to get the most side wall and tire width as possible.

Any advice would be greatly appreciated. Thanks!