2007 FORD E-450 Wheels Problems

WHILE ON A TRIP AND WHILE RETURNING HOME THE R/R INSIDE TIRE TREAD SEPARATED CAUSING THE VEHICLE TO SWAY. I WAS TRAVELING ON HIGHWAY 231, A 4 LANE HIGHWAY,. I WAS TRAVELING 65MPH AT THE TIME OF THE TIRE FAILURE. I WAS ABLE TO PULL INTO THE FLORIDA WELCOME CENTER LOCATED ON THE FLORIDA ALABAMA LINE. I HAD TO CALL SOMEONE OUT TO CHANGE THE TIRE. AFTER RETURNING HOME TO PANAMA CITY, FLORIDA I TOOK THE VEHICLE AND TIRE BACK TO PEP BOYS TO HAVE IT REPLACED. I ADVISED THE SERVICE WRITER THAT I HADE PURCHASED ROAD HAZARD INSURANCE WHEN I PURCHASED THE TIRES AND ADVISED HIM AS TO WHAT HAPPENED AND HE ADVISED ME THAT TIRE SEPARATION WAS NOT A ROAD HAZARD AND THAT I WOULD HAVE TO PAY 50.00 DOLLARS TO HAVE THE TIRE REPLACED. THE TIRES I BOUGHT FOR MY MOTOR HOME WERE DEFINITY DAKOTA H/T LT...