15x7 4 1/8 bs- largest tires?

I have 255/60R15 on my 66 Valiant and they fit nice, no rubbing but I am running MP S/S springs so it is higher. I have run this tire on a stock 15x6 Mopar wheel, 15x6 Torq Thrust's and currently on 15x7 Cragar S/S's :glasses7: