Robert,
You say the RF tire rubs on the front of your wheelwell, where the fender curves in and meets up with the front bumber, but it only rubs if you're backing up and cut the wheels hard left? Are you saying that if you're on a flat surface like a parking lot, when you turn hard left you have no rub with the car stationary or moving forward in a hard left turn, but if you stop and reverse direction your RF tire starts rubbing? If that's the case you have something loose or severely worn in your front end, likely the ball joints? Have you checked out your front end components? Had the car aligned?