Just out of curiosity how does the brake setup change things? I'm using a 74 front suspension.
Remember backspace doesn't care how wide the rim is. Backspace in the front gives you an idea of the clearance between the rim to the suspension pieces and clearance between the frame/innerfender and tire.
As i understand it the outer fender space varies. I believe Dusters have a wider fender than Darts and Demons. No idea where Cudas fit in. Does this not make the backspace requirement different for these cars?
I was thinking in terms of the effect of backspace on outer fender clearance when I talked about an 8" rim needing 1/2" more backspace than a 7" rim. This should put the tire in the same place relative to the outer fender.
Regarding the suspension side I am under the impression that an 18" rim clears any ball joints so my focus has been on the outer fender clearance.
You may run into sway bar interference with high backspace rims with an original 67-72 wide style front sway bar.
I was unaware of sway bar clearance issues and had planned to run the bar that comes with the 74 suspension that I'm using. Changing to one of the aftermarket ones should not break the bank.
My top of the fender lips are rolled and the bottom front corner of the lip is bend in about 2".
I was planning to roll the fenders. I'll do the fender bender too if needed.
I hope you don't mind all the questions. This info is hard to come by. I was emailing with Coys wheels but I think they got tired of my questions and quit replying. So... Many thanks!