How to read truck tyre markings
Different types of vehicles need different tyres. Information about different tyre properties for specific applications is indicated on each tyre model in the form of various sidewall markings.
How to choose the right tyres for your truck?
When buying truck tyres, you should choose reliable suppliers, such as SklepOpon.com, which cooperate with major tyre manufacturers. In this way you can be sure to obtain tyres of the highest quality.
Truck tyre size markings
The size markings for truck tyres are very similar to those used on passenger car tyres. They consist of three basic elements: section width, aspect ratio or profile, and the rim diameter. An example of a popular truck tyre size is 315/70 R22.5 154/150 L.
The first number, 315, indicates the tyres’s section width in millimeters. The second number, 70, indicates the tyre’s aspect ratio, i.e. the height of the sidewall expressed as a percentage of the section width. In this case, it is 70% of 315 mm, i.e. 220.5 mm. The last number, 22.5, is the rim diameter in inches. The letter “R” indicates that the tyre carcass, which is an element of its internal structure, has a radial construction.
The remaining characters, 154/150 L, denote the load index and the speed symbol. The first of the two numbers (154) represents the maximum load (in kg) that the tyre can carry during single tyre assembly; in this case it is 3750 kg. The second number (150) indicates the maximum load during dual tyre assembly (3350 kg). The letter “L” indicates the maximum speed of use, which in this case means the tyre can be used at speeds of up to 120 km/h. All these properties should be selected strictly according to recommendations of the vehicle/trailer manufacturer.
Markings specifying tyre position
Truck tyres are divided into three basic types depending on the axle they are being used on: steer axle tyres, drive axle tyres, trailer axle tyres:
- Steer axle tyres are usually marked with the following symbols: F (Front) or S (Steer).
- Drive axle tyres are usually marked with the letter D (for Drive).
- Trailers/semitrailer axle tyres are sometimes marked with the letter T (for Trailer). Another designation that can also be used is FRT (Free Rolling Tire). Tires with the FRT symbol are designed for trailers or semi-trailers but can also be fitted on axles other than steer and drive axles of a motor vehicle.
It is worth noting that only the FRT marking is a legally approved marking, which is defined in UNECE Regulation No. 54, paragraph 3.1.15. The use of the remaining symbols (F, S, D and T) is not regulated by law and tyre manufacturers may use other symbols.
What does “regroovable” mean on truck tyres?
Unlike passenger car tyres, truck tyres can also be marked with the word “regroovable”, which indicates a tire manufactured with an extra layer of rubber between the cord body and the original tread to enable recutting or regrooving of the original tread pattern, which extends the life of the tyre.
Regrooving can only be performed at authorized operators. Tyre manufacturers strictly define the regrooving parameters of specific tyre models, which include the depth or width of cuts. Regrooving is not allowed when the tread is damaged, as any damage affects the tyre structure and may lead to the corrosion of the metal elements of the tyre’s internal structure.