I ran 275/60R 15s (Firestone Indy 500s) on 15x8s on a '74 Duster, need 4.25BS as Scott says. Quick fix is .250 spacers IF there's enough lugnut engagement and you're stuck with 4.5BS. With these 275s, I did have to space the ft spring brackets back 1/4". The car had its original rearend, springs, & ride height.