THE VEHICLE WAS TRAVELING ON IN TOWN HIGHWAY SPEEDS BETWEEN 25-55 MILES PER HOUR FOR APPROXIMATELY 10 MILES WHILE TOWING A 14 FOOT TRAILER. AS I APPROACHED AN INTERSTATE ON RAMP IN WINCHESTER, KENTUCKY, I SMELLED SMOKE AND PULLED OVER TO INSPECT THE VEHICLE. THE SOURCE OF THE SMOKE/FLAME WAS COMING FROM THE REAR MUFFLER PIPE FIBERGLASS HEAT INSULATOR (TOYOTA PART NUMBER 58155-60100). THE FIBERGLASS HEAT INSULATOR HAD DRY ROTTED AND WAS RESTING ON THE REAR MUFFLER PIPE AS IT BENDS OVER THE REAR AXLE. I WAS ABLE TO CRAWL UNDER THE TRUCK AND PULL THE INSULATOR OFF THE BOTTOM OF THE TRUCK AND EXTINGUISH ON THE SIDE OF THE ROAD. AFTER DISCUSSING WITH TOYOTA DEALER, NO PRODUCT RECALL HAS BEEN ISSUED BUT THE PART HAS NOW BEEN REMANUFACTURERED OUT OF TIN/ALUMINUM TO REDUCE THIS RISK. DUE TO THE HIGH RISK FOR FIRE / INJURY THAT IS VERY NEAR THE GAS TANK, SHOULD THIS BE ISSUED AS A MANUFACTURER RECALL?