72 Duster Tire/Rim Size?

Backspace is the distance from the lug nut holes, to the edge of the rim. This is on the backside ( or inside) of the rim. I hope this makes sense. Anyway 4-1/4" to 4-1/2" is what should work for the front of your duster. Any wheel company will know what bacspace is, but be sure to tell them what you want.