What does ST on tires mean?

[OChristopher]

Tire ST stands for Special Trailer, indicating tires designed for trailers commonly towed behind private vehicles in Europe and America for transporting goods or travel purposes. Trailer tire specifications: Automobile tires can be categorized into pneumatic tires and solid tires based on their carcass structure, with most modern vehicles using pneumatic tires. According to internal air pressure levels, pneumatic tires are divided into high-pressure, low-pressure, and ultra-low-pressure tires, with low-pressure tires being widely adopted by various vehicles. Pneumatic tires are further classified into tube-type and tubeless tires based on construction. Passenger cars predominantly use tubeless tires. Depending on the arrangement of internal cord plies and breaker layers, tires can also be categorized into radial and bias-ply tires, with radial tires being the standard for automobiles.