1889, Scottish surgeon Deng Lupu invented the world's first pneumatic tire. 1959, Michelin Company of France invented the first tubeless tire, and vacuum tire gradually replaced pneumatic tire as the most widely used tire. What is the principle of vacuum tire? Why can't there be air leakage without an inner tube?
In fact, the vacuum tire is not completely vacuum, but the inner and outer tires are integrated, and the outer tire also serves as an inner tube. Its inner wall has an airtight layer of two to three millimeters. After inflation, with the increase of air pressure, the tire will press the hub more and more, forming a good air tightness. Moreover, the air nozzle of the vacuum tire is directly installed on the hub, and the air nozzle and the hub are also sealed, so the vacuum tire will not leak air under normal circumstances.
In addition, vacuum tires are far superior to traditional tires in other aspects. First, it has strong puncture resistance and is safer. Good self-sealing ability is that once the vacuum tire is punctured, it will not deflate instantly like ordinary tires, but will leak slowly, which improves the safety of high-speed driving. Second, wear resistance is more economical. The diameter of the vacuum tire rim is relatively large, so it will not be affected by the heating of the brake drum during driving. Because there is no inner tube, there is no friction between the inner tube and the outer tire, and the tire and the hub are closely attached. When the vehicle runs at high speed, the high temperature generated by the friction between the tire and the road surface can be quickly dissipated by the steel ring, and the tire wears evenly due to its uniform ground pressure, thus prolonging the service life of the tire. Third, the comfort is higher. Due to the close contact between the outer tire and the wheel hub, the lateral swing amplitude of vacuum tire is relatively small, and its comfort and stability are much better than that of ordinary tire when driving on rough road.
In this way, compared with ordinary tires, the practicability of vacuum tires has been improved a lot. However, vacuum tires can also puncture. Because the sidewall of the vacuum tire is thin, once the tire is punctured and leaked, the air pressure in the tire will be too low. In addition, severe wear will increase the risk of puncture of vacuum tires. There is a triangular wear mark on the side of the tire. When the tire is worn and touches the triangle corner, it must be replaced. There is also a mark in the groove of the tire, and there is a raised mark in the groove with a height of1.6 mm. When the tread is worn flush with the mark, it should also be replaced in time.