Originally Posted by johnlewis
ST tires are supposed to be used on travel trailers and 5th wheels.
Actually that's the trailer manufacturer's call. They can use any DOT certified highway tire they deem an appropriate fitment. Only the vehicle manufacturer has that option.
It becomes a confusion factor when people see RV trailers of equal size and weight, from a different manufacturer or even the same manufacturer, having been fitted with tires with a size designated design other than ST. It's not an open door to use them. The vehicle federal certification determines the size designation tires to be used for each individual