Tire size: specification is the symbolic data of tire geometric parameters and physical characteristics. Tire size is usually represented by a set of numbers, the former number represents the tire section width and the latter number represents the rim diameter, all in inches. The letters or symbols in the middle have special meanings: "X" stands for high pressure tire; "R" and "Z" represent radial tires; "One" refers to the low-pressure tire. Level: Level refers to the nominal number of plies in the tire rubber layer, which is not completely consistent with the actual number of plies, and is an important indicator of tire strength. Grades are marked in Chinese, such as 12; Sign in English, such as ""14p. R ",namely 14 layer pole.