1966 valiant rim width with spacers

I have ran a 14x7 with 4.25 back space, my buddy runs a 245 60 15 and now a 255 60 15 on a 15x7 with 4 3/8 back space. But that is a tight I mean tight fit, but works. That’s with a 8 3/4 axle small bolt pattern. You’ll probably just have to add the spacer size to the overall back space you need. Good luck.