i have a 71 mach 1 with 4 wheel disc i am tring to buy these bilitt specialties 15 in wheels my disc in the rear are gm metric they touch the inside of my 15 x 10 centerline the mesurement i came up with was almost 5in backspace how do 1 keep 15s and buy new street light rims do i have to go to a 16

 

Welcome to the board!

I wish I could help, I am totally ignorant as to how to care and fix the classic 60's & 70's Stangs.

But try in here to find the answers:
https://mustangforums.com/forum/classic-mustangs-16/