widest tire on 6 inch steelie?

so I've been running 245-60 14 BFG TA radials on stock ralley wheels for 25 years on 3 1970 Darts and on 6 inch Specialty Wheels ralleys. Well over 100,000 miles of experience with this combination - no blow outs, no sealing problems, not even uneven tread wear. I'll compare this experience to a theoretical chart any day... REAR WHEELS ONLY!!! Fronts are 205 70 14 gives you the same side wall height front to back, but 215 70 14s will fit - anything taller and you fight with scrubbing the frame in the back and the fender corner in the front when you turn the wheels.