What are the model specifications of semi-trailer tires?
3 Answers
Semi-trailer tire models range from 8.25R steel tires to 12.00R steel tires. Below is relevant information about tire models: Tire specifications: Tire specifications are commonly represented by a set of numbers. The first number indicates the tire section width, and the second indicates the rim diameter, measured in inches. For example, 165/70R14 denotes a radial tire with a section width of 165 millimeters, an aspect ratio of 70, and a rim diameter of 14 inches. Some tires may include additional letters or symbols with special meanings: "X" denotes high-pressure tires; "C" denotes reinforced tires; "B" denotes bias-ply tires; "-" denotes low-pressure tires. M and S are abbreviations for Mud and Snow, respectively, indicating that the tire is suitable for use on snowy and muddy roads. Tire model: Tire model markings mostly appear as: 215/70R15, where the numbers represent the following: 215 indicates the tire section width in millimeters; 70 is the aspect ratio, representing the ratio of the tire sidewall height to the tire section width, with 70 indicating 70%; R is the abbreviation for Radial, indicating the tire has a radial structure; 15 is the outer diameter of the rim in inches.
For us long-haul drivers, tire specifications are of utmost importance. With twenty years of experience driving semi-trailers, I can say that the drive axles on the main truck are now mostly equipped with 315/80R22.5 vacuum tires, while the trailer wheels commonly use 295/75R22.5. I remember specifically comparing them when changing tires last year—295s are narrower than 315s but more fuel-efficient, making them ideal for standard load transportation. The steering axle must use high-speed tires with all-position treads, the kind marked with "STEER" on the sidewall. When driving to Northeast China in winter, we have to switch to snow tread tires, and those special specifications with stud holes in the sidewalls need to be ordered in advance. They must also match the wheel rim specifications, or else the tires can easily come off—a lesson learned the hard way.
Having repaired truck tires for over a decade, trailer tire specifications primarily depend on the trailer type. Standard freight semi-trailers commonly use 11R22.5 load range 16 tubeless tires, while heavy-duty trailers like tankers require 315/80R22.5 load range 18 tires. Pay attention to the speed rating symbol on the tire sidewall - vehicles transporting hazardous chemicals must use L-rated tires capable of over 130km/h. Recently, a trailer had severe tire wear issues, which turned out to be caused by using undersized 385/65R22.5 tires that didn't match the axles. Nowadays, new lightweight trailers are trending toward 295 tubeless tires, which can be 40kg lighter per tire compared to 12R22.5 models.
