Wheel Size for 1968 Barracuda

I’ve had 245/60/15 with 15x7 and small bolt pattern axles in the rear of my 68 Barracuda coupe with 100% OE untouched quarter panels

My car had original rear leaf springs and was not jacked up in any means.

I should ok 255/60/15 with 15x7 with 4.25” backspace. Same with 15x8 4.5” backspace.

If you get a little inner tire sidewall to spring rubbing, add 3/16” spacer