They'll fit but you'll find that the tire manufacturers do not recommend it. I ran 275 Nitto's on my stock wheels all last year. Plenty of people do it without a problem. Others will recommend you not.
It's one of those comfortability issues. If you can move up to a 9" wheel in the rear, I would do it. I just got 10.5's and hetting ready to buy the 315's
I see it all the time on the stock 17x8 wheels, so i think you'll be fine. The only thing is you'll have a bit of tire bulge in the rear which could make the rear feel mushy during hard cornering