Anybody here running a 315/35/20 on a 4/6 drop?

I'm thinking if I widen a stock 8.5 SS wheel to 10 inches, increasing the backspacing, where the extra tire would be inside of the fender, it should not rub. Thoughts?

I know a 275/45 20 will not rub and it's slightly taller than the 315/35.