Front tire and rim size, Help.

I have decided to go with American Outlaw i 15"x8 (with 4" BS) on the rear, with MT sportsman ST 275/60r15.

On the front will be American outlaw i 15"x6, but unsure about Backspacing and tire size. The most narrow Sportsman ST is 215/70r15, would that work? Right now I have 205/75r14. I kinda wanted to have the same tires on all 4 but am open to suggestions.

Would the 215/70r15 fit best on a rim 6" wide? What would the backspacing be?

Thanks,

Richard