Hey guys, I pull a 16'x7' Haulmark trailer around town every day(March-November). Loaded, I would say it weighs about 6k lbs. The problem I am having is that I go through 4-5 sets of rear tires in these 9 months. Tire size: Towmaster 205-75-14. The hitch is set so that the trailer is sitting level. Any suggestions why this is happening, and how to fix it. Thanks