I am running a 33x10.5x15 BFG AT on stock steel rims with a 3" Suspension lift.

with the 31x10.5 you won't have any issues.

With the 33x10.5 you'll need to trim a hair more than with the 33x9.5x15. And you'll probably pay less per tire too.

You may want to double check your steering stops...if they are worn out, you may start rubbing on the inside edge of the tire against the wall of the wheelwell or the shield over the brakelines.