15x7 Rally,s on rear of 66 Dart

Thanks Oldmoparsrule,I,ve swapped out the 7 1/4 sbp and put in a 8 3/4 bbp with Moser axels.I found some 15x7 bbp rallys that I,d like to use with 14x6 rallys up front.Still looking for the biggest 15 inch tire I can fit in there?