Why are the wheels round, and why are the axles mounted on the center of the circle

1, the wheel is round: it can ensure the smooth movement of the track. If it is square, triangular, or other polygon, or even oval, it will move high and low, and the car can not guarantee stability. 2. Axle: installed in the center of the circle. It is not installed in the center of a circle, so its trajectory becomes no longer circular. 3, the wheel is a rotating component between the tire and the load borne between the axle, usually composed of two main components, the rim and the spoke. The rim is the part that mounts and supports the tire on the wheel, and the spoke is the supporting part on the wheel between the axle and the rim. In addition to the above components, a wheel sometimes includes a hub. 4, classification, according to the structure of the spoke: the wheel can be divided into spoke plate wheels and spoke wheels. According to wheel material: can be divided into steel, aluminum alloy, magnesium alloy and other wheels. One or two tires are mounted on one end of the axle: it can be divided into single wheels and double wheels. 1, check the tire, if the tire is cut on the side of the tire or the depth of the groove on the wheel has been worn (the depth is less than 2 mm), the degree of serious can not be repaired, you need to replace the tire. 2, the tire can not change the size at will, you need to choose the tire with your car. 3, because the sealing performance of tires and wheels is very good, it is necessary to use professional equipment to separate the tires from the wheels; To rotate the tire evenly, so as not to damage the wheel hub. 4, the tire is completely removed from the hub, when the tire is removed, at the same time to check whether the hub is injured. If the tire is installed, not only the seal is not tight, but also the risk of breakage. 5, the tire is specially designed with yellow dots and red dots, because the wheel in rotation, there is a center of gravity, the yellow dot side is lighter, and the red dot is a focus. Therefore, when installing, pay attention to the place where the yellow point is aligned with the valve nozzle. 6, if the installation is difficult, you can use the tire, after the new tire is installed, pump enough gas to prepare for the subsequent balance. 7, the installation of new tires, be sure to do dynamic balance. During driving, if the position of the tire is unbalanced, it will cause the shaking of the steering wheel, the faster the speed, the greater the vibration; Also, unbalanced tires can cause wear and tear. The measurement of dynamic balance has a certain value, when rotating, you can measure the weight difference, according to the machine test shows that the tire, the left difference of 15 grams, the right difference of 11 grams. Reference: Encyclopedia - The Wheel