2001 ITASCA SPIRIT Tires Problems

ON 2001 ITASCE SPIRIT 31T MOTOR HOME ON A FORD 450 CHASSIS I EXPERIENCED A BELT/TREAD FAILURE OF A FIRESTONE STEELTEX R4S LT225/75R16 TIRE ON THE INNER DRIVERS SIDE REAR DUAL WHEEL POSITION. THERE WAS A LOUD RUMBLE WHICH I AT FIRST THOUGHT WAS CAUSED BY PAVEMENT ROUGHNESS. I SLOWED DOWN FROM APPROX. 60 MPH AT WHICH TIME THE TREAD LET GO WITH A LOUD NOISE. FORTUNATELY I WAS ABLE TO CONTROL THE VEHICLE AS THE OUTER DUAL TIRE HELD. UPON INSPECTION THE INNER HALF OF THE TREAD HAD LET GO, CAUGHT THE 1/16" METAL PLATE HOLDING THE MUD FLAP WHICH IT BENT UP OVER THE TIRES PREVENTING SECONDARY DAMAGE TO THE WHEEL WELL OF MY MOTOR HOME. I TRIED CONTACTING FIRESTONE AND WAS SENT ON A WILD GOOSE CHASE TO END UP ON A VOICE MAIL AT THE DAYTON ENGINEERING CENTER. I AM REPLACING ALL 7 OF THE TIRES...