Carlstar RADIAL TRAIL HD ST175/80R13 - 91M (6 ply)

The maximum speed varies by model, but it generally falls between 105 and 130 km/h (65 to 80 mph) based on the speed rating printed on the sidewall. For safe driving, it’s recommended to stay 8 to 15 km/h (5 to 10 mph) below this limit, especially in hot weather or under heavy load, since excessive heat combined with speed accelerates tire degradation.

Yes, tire age matters just as much as visible tread wear, since the rubber in ST tires naturally degrades over time, even without heavy use. It’s recommended to check the DOT code on the sidewall to find the manufacture date and replace the tires after 3 to 5 years, regardless of their appearance.

Uneven wear usually comes from misaligned axles, incorrect tire pressure, or an overloaded trailer that distributes weight unevenly across the tires. Even slight misalignment can accelerate wear on one side of the tire, while underinflation wears down the shoulders more and overinflation wears down the center of the tread.

Extended idle time, especially while the trailer remains loaded, promotes premature rubber aging and can cause flat spots or sidewall cracking. It’s recommended to move the trailer periodically, elevate the axles if storage exceeds a few months, and check tire pressure regularly even when not in use.

ST stands for “Special Trailer,” a tire category designed exclusively for trailers rather than motorized vehicles. Unlike LT or passenger tires, an ST tire has stiffer sidewalls that reduce sway and improve lateral stability for a loaded trailer, but it’s not built to steer or power the wheels. These tires are also engineered to run at their maximum sidewall-rated pressure, unlike passenger tires adjusted based on actual vehicle weight. Note that ST tires age over time even without heavy use; it’s recommended to replace them every 3 to 5 years, regardless of how the tread appears.