The most common signs on tires are the tire brand, followed by the tire specifications, and then the load index and speed signs. For example, 205/55R16 91V, the value 205 represents the tire width (mm), 55 represents the aspect ratio (the percentage of sidewall thickness and tire width), R16 represents the wheel diameter, and 91 represents the load factor, V represents the speed coefficient.

There will be special tables for the load factor and speed factor, and you can check their corresponding maximum load capacity and maximum safe speed. For example, a load index of 91 represents a maximum load of 615kg per tire (as shown in the figure below). The load index is engraved on the sidewall, indicating the maximum load limit of this tire. For driving safety, this load limit cannot be exceeded.

Extended information:

Tire specifications are often represented by a set of numbers. The first number indicates the tire section width, and the latter number indicates the rim diameter, in inches. For example, 165/70R14 means the tire width is 165 mm, the flatness ratio is 70, and the rim diameter is 14 inches.

The letters or symbols in the middle have special meanings: "X" represents high-pressure tires; "R" and "Z" represent radial tires; "one" represents bias tires. For example, 6.00-12, bias tires are only used on some low-end off-road vehicles and heavy trucks due to their poor safety, load capacity and high-speed stability.

The maximum speed at which a tire can carry a specified load under specified conditions. The letters A to Z represent the tire's certified speed rating from 4.8km/h to 300km/h. Common speed grades: Q: 160km/h; R: 170km/h; S: 180km/h; T: 190km/h; H: 210km/h; V: 240km/h; W: 270km/h; Y: 300km/ h; Z: ZR speed is higher than 240km/h.

Baidu Encyclopedia-Car Tire Marking