The tyres are divided into pneumatic tires and solid tyres according to the different structure of the tire. Most modern cars use inflatable tires. According to the air pressure inside the tire, inflatable tires can be divided into high-pressure tires, low pressure tires and ultra low pressure tires three kinds. Low pressure tires are commonly used in all types of automobiles. The inflatable tires are divided into two types: inner tyre and no inner tyre. The car is generally used without inner tyre. The tyre can be divided into two types: radial tire and oblique tire, according to the different arrangement of the inner ply and cushion layer. Radial tires are commonly used on automobiles. The tire side is marked.