I have got 285's, but they are close to being done and I am putting 315's on next. I just put a leveling kit on and now there is a lot of room up front.
yup 315's will fit... You'll want to play with the air pressure front to rear though to get them to wear decent.. My 315's and 325's have seemed to like low to mid 30 psi for them to wear even in the rear.