anybody runnin 15x11 rims?

[lester622]

im thinkin about gettin some bogart 15x11 rims but i dont know what backspacing to get and there backspacing runs in stupid numbers, i have a 71 12 bolt and i seen on here somewhere that its 1 7/8" wider from drum to drum but idk if thats each side are all together. I dont have a frame notch at the moment but the body is coming off one more time so i may end up doing one. does anybody know what size backspacing i would need there backspacing goes from 3.375" - 7.375" ............... i have on it now a 15x10 with 5" backspacing and the stock rear and i have about a 1/4" from the frame rail and it doesnt hit the fender lip but idk what its gonna be when i put the 12 bolt in