64 dodge polara back spacing ?

Putting torque thrusts D on 500 model. Original steelies were 3 and one half. Want to use a 8 inch rim. What back spacing has worked for someone if putting on 255-60?

Got the same question for a '64 Sport Fury. I know a guy out west that had 15X8s with 5" b.s. and ran a 30" tall by 10" cheater slick on a '63 Polara. Most guys here will tell you 4-1/2" to 5" b.s.will work. There's a good thread regarding wheel selection for a '65 Coronet in this section-with pics! Spring choice will also come into play;S/S units may give you more room than standard pieces.

Thanks for the help. The way I was measuring came out t 4-4 and one half. Feel more confident with the extra feedback.