pretty much. the 17s come in 10.5. the 18s are 10s. you will have to massage the inner fender with a BFH. you should roll the outer fender lips. i havnt rolled mine in a year, but that will be happening next week. i did damage the tires when i was moving back from college due to the excess weight and an expansion joint on the interstate. tires hold air fine, but it did put a slit in the sidewall.
running a 315 will be doubtful. unless your willing to minitub the car, and possibly narrow the rear end a half inch.
mine cleared my tailpipes just fine, but then i cut them off a few months later anyway.
im running a 275/35, but will be stepping up to a 275/40.