What Offset Would You Need For 17"x9.5"

[GT086]

Even though I'm pretty much set on running 17"x8" size wheels up front and 18"x9.5" wheels out back I'm curious as to what offset you would need on a pair of 17"x9.5" wheels to make them fit with 275/40/17's without rubbing? Even if you had to roll the fenders.

[Venom]

No matter how wide the wheel is or how large the diameter is, there is a perfect offset that centers the wheel exactly for any size. I believe that offset is +52 for the rear. I say that because my wheels are 18X9 +52 and my BFG 275/40/18s rub both sides of the wheel wells equally.

EDIT: and I do have the fenders rolled maximum.