1973 scamp front tire size.

Maybe I missed it, but what bolt pattern and brakes are you running?

15x7 with a 4.25" backspace is pretty much the best you can do with a 15" rim. 3.75" backspace really isn't enough for a 7" wide rim, even with SBP brakes, if you want to maximize your front tire size.

With the 73+ BBP mopar brakes a 15x7 with 4.25" backspace will take up to a 225/60/15, which is pretty much as big as you can go with a 15" rim up front.