they are 17x8" wheels...and 315's definately won't fit and 275's are a tight tight squeeze and will have some bulge to them...I'd stick with either 245/45's on the stock rims...get some 9" wheels if you want the 275's and 10.5" wheels for the back if you want 315's...
some guy just borrowed my stock 17x8's to drive up to WFC8, and was putting 315's on them. I guess he made it there and back, but I wouldn't recommend it. a 245 is 9.6" wide roughly, and a 315 is 12.4" . Click on my link below, there are some pictures of 295/35 tires on a 10" rim. for a 315 you need atleast 10+" 's wide. They would probably spin off of your wheels. they look right on an 11" wheel. my 2 cents
I have 285's on the back on 10.5" rims. 315's would fit, but probably rub on quads or exhaust. It really depends on the brand of tire. BFG's and Goodyears run really wide. Nitto's run really narrow. The largest you are supposed to put on an 8" rim is 255's.