New wheels and tires

Greetings all;

I have finally gotten my brakes all changed out with disc's on the front and new drums on the back. Changed out to the big bolt pattern and now in need of new wheels and tires. What is the largest size that I can put under the rear without modifying the wheel well? The car is a 1972 Demon. I want to stick with the good old Crager S/S's to keep the old school vibe and look, but will entertain others. Thanks for your time and input.