Java,
There is one place in the rear fender that can be responsible for chewing off of your tire before the rest of the fender would, and you can actually reduce the damage by cutting this part off with a dremel tool. Look inside the fender where the rear bumper meet the car; you can actually see the skid mark that left by the rubed tire against the plastic part which belong to the bumper and it should be in a triangular shape. So the solution is to cut a larger triangular peice, larger then the left skid mark out of that plastic bumper and leave the srew that held the bumper to the car. After done that for the first time you would want to test drive the car to see if the problem persist, if it is then you have to see to the location of the new skid mark and repeat the cutting process. You may have to repeat this step several times to create enough clearance for the tire or reduce the effected surface. It is kinda weird that the rear tire doesn't bounce upward directly into the fender on top but instead toward the back of the vehicle! Cutting something off of the stewie is nerve wrecking so be careful, and practice make perfect!
Oh, and if the skidmark is on the metal surface of the vehicle then you have to bring out the louiseville slugger
Hope this helps!