What size tires will fit on stock dart 15" wheels?

Also, I'm running 383 with 8 3/4 and 727... lots of HP on those rear tires... will 8 inch tread be sufficient?
With 3/4 offset springs n such, you said +6mm offset was good which is what the 15x7's are...
the list says I can fit P255/60R15 on a 15x7 wheel and the tread width would be 8.2