It's because they're Goodyear Marathons among other things. They don't have a very good reputation. Try a set of Maxxis tires instead, they seem to workout better. Also check and make sure your tires are inflated to the maximum pressure as stated on the sidewall. Look at the tires and see if the tread is wearing evenly. Often people hit curbs when turning and the right front tire is the one that gets hurt. Be careful not to do that. If the tire starts to wear unevenly bring the trailer to a big truck/trailer alignment shop and get it aligned. RV dealers don't have the equipment/expertise to that. Precision Frame and Alignment in Elk River, MN,is a GREAT place to have that done. RV dealers will only sell you a new axle at a much greater cost. Good luck.
B.O.