Paul-
I'm using 17x9-1/2 Centerlines in the back, with 6" backspacing. Don't have tires on the rims yet, but from what I can tell after measuring them, I shouldn't have a problem. The FFR manual says to use 6-1/8" BS with 17" wheels in the back.
For the front, FFR recommends 5" when using 17" rims. I'm using 5-1/2" and a 1/2" wheel spacer due to fitment issues with my brake calipers.
Some people have experienced rubbing of the inside of the front tire on the F-panels or the tie rods at full lock. Some have added some sort of device to limit lock-to-lock, while others simply live with it.
2FAST