It mostly depends on offset and tire size.
You are looking to get a 17x8, so I assume you want a fairly fat tire in the back. A 17x8 + 38 should fit nicely on the back with a 235/40/17 tire, without any rubbing issues. Of course, it will give it a slightly "tucked" look in the rear. But should still be pretty close to the fenders.
With this rear, the front should get a 17x7 +30 to +40 (anywhere in there should look ok), with a 215/40/17 tire.
Of course, slight changes can be made here and there, depending on brand and what not.
I personally, recommend rolling the rear fender and sticking a 17x9 back there! Looks a hell of a lot better, if you ask me!
Good luck!
Frank