Which backspacing for front of 69 Barracuda

4.25" backspacing for best fit. I'd run 15x7's with 215/60/15 or many times 225/60/15 tires will fit but there are variables and some people have had issues. 15x6 with 4.25" backspace will give you a little more room than a 15x7 with 4.25" backspace.