Trailer Tires (ST Tires)
Trailer tires are one of the most safety-critical parts of your rig, and buying the right ones matters more than most people realize. Tires4That stocks a wide selection of ST (Special Trailer) tires in both bias-ply and radial construction, covering the most common sizes for utility trailers, boat trailers, cargo trailers, car haulers, horse trailers, and equipment trailers. All at prices well below what you'd pay at a tire shop.
What To Look For In A Trailer Tire
Always look for the 'ST' prefix on a trailer tire. It means the tire was engineered specifically for trailer use. ST tires have stiffer sidewalls than passenger (P) or light truck (LT) tires, which reduce trailer sway and allow for the higher inflation pressures needed to carry heavy, sustained loads without overheating. When selecting a trailer tire, match the size and load range to your trailer's VIN plate or owner's manual d. Load range C (6-ply, 50 PSI) is adequate for small utility trailers. Load range D (8-ply, 65 PSI) is the most common for travel trailers and cargo trailers. Load range E (10-ply, 80 PSI) and above handle heavy fifth wheels, car haulers, and equipment trailers. Always inflate trailer tires to the maximum pressure printed on the sidewall.
Frequently Asked Questions
Q: What does 'ST' mean on a trailer tire?
A: 'ST' stands for Special Trailer. It indicates the tire is engineered specifically for trailer axles, with stiffer sidewalls, heat-resistant compounds, and construction designed for free-rolling axle loads rather than steering or powered drive use. You should never use passenger or LT tires on a trailer, as they lack the sidewall stiffness needed for safe towing.
Q: What load range do I need for my trailer?
A: Check your trailer's VIN plate or owner's manual for the required load range. As a rule of thumb, small utility trailers can often use Load Range C (6-ply). Travel trailers, boat trailers, and cargo trailers typically need Load Range D (8-ply) or E (10-ply). Heavy equipment and car haulers usually require Load Range E or higher. Always choose a load range that meets or exceeds the trailer's GAWR.
Q: Should I choose bias-ply or radial trailer tires?
A: Radial trailer tires run cooler and last longer at highway speeds, making them the better choice for trailers used frequently or for long-distance towing. Bias-ply tires have stiffer, more damage-resistant sidewalls, which is a practical advantage for trailers used on rough job sites or stored for long periods. For most recreational and utility trailer applications, radial is the preferred option.
Q: How often should I replace trailer tires?
A: The U.S. Tire Manufacturers Association (USTMA) recommends inspecting trailer tires annually and replacing them every 3–6 years, regardless of tread depth. Trailer tires are prone to UV degradation and dry rot from sitting, which can lead to sidewall cracking and blowouts even on tires that appear to have good tread.
Q: Should I inflate trailer tires to the max PSI?
A: Yes, unlike passenger car tires, trailer tires should be inflated to the maximum cold PSI printed on the sidewall. Running at lower pressure reduces the tire's load capacity and causes excessive heat buildup, which is the leading cause of trailer tire blowouts.