15x4 & 15x7 stock steelies?

I could be wrong but I swear the Dippy 7'' wheels are 4 1/4'' backspace. A friend runs 15x8, 4 1/4 back space steelies (Stockton made) on his Duster with 275/60/15 BFG drag radials and they fit just fine.

they are 4 1/4 , the angle of the pic is off LOL . i happen to have pics