ST or (special trailer) tires are specialty tires that are designed especially for trailers. They are constructed to provide safer driving experiences at high speeds. Like any other vehicle that travels at high speeds trailers tires are subject to blow outs and low inflation. Choosing tires that are appropriate for the highway, and tires that can with hold heavy loads is important. The majority of accidents that takes place on the highway are due to tires that have come unthreaded or at the least are they are not equipped for over the road travel.
ST tires provides this kind of protection for on the road drivers. Since these radial, all purpose, ultra sports tires are strictly for trailers they must pass state inspections. The United States Department of Transportation must approve the safety of these tires before they are classified as ST tires. These tires are tested before they are released and put out on the open market. There is no time as to when a blow out may occur; the driver can be across country or on the interstate. Regardless of how long or how short the trip is having ST tires put on the trailer is 'smart traveling.'