In my experience this combo is the biggest that could be fit PERFECTLY on a 71 Demon with no spring or body modifications. Enough clearance for the tires inboard and outboard with room for growth and side wall flex, no rubbing anywhere.
Mickey Thompson 255 60R15 ET Street Drag Radials 27.00 dia.
Summit Racing 15 x 8 SBP Wheel (4.250 back spacing is the key) Code WVI-61-5754044
205 75R 14 on the front, also 27.00 dia
The cars stance with this combo is right on the money as well.
