Chris please read the post above.....Nitto's run thinner than a regular 315. I'm sure you know this.....a BFG 315, yes definetly use a 10.5 rim. But Nitto's 315 is about the size of a BFG 295...it is plenty safe. Do a search and see how many dozens if not more run the Nitto's on the stock 17X9 wheels....
Here's a pic of how the Nitto's look on the stock wheels....