Hub "means the cylindrical central part of the wheel.
The automobile wheel hub refers to the accessories used to bear the hard moment of inertia between the automobile and the tire, which can also be called rim, steel rim, etc. The complete wheel hub unit, including the automobile bearing, namely the flange plate, supports the wheel with the tire. It mainly affects the size of the brake specifications and the selection of tire specifications. The larger the wheel hub, the lower it can be. The larger the brake system, the wider the wheel hub, and the wider the tire with higher performance.
Early cars did not have car hubs, but used simple double bearing units, using nearly solid tires. Solid tires were extremely poor in terms of performance, driving comfort, etc. The wheel hub and tire cooperate with each other, and the tire is responsible for directly contacting the ground and bearing the soft pressure of the vehicle's driving inertia, and then the solid wheel hub bears the hard inertial pressure.
In fact, it is the tire that has the greatest impact on the braking performance of the car. A tire with better performance can reduce the distance from braking to standstill by several meters at 100 kilometers per hour. For example, it is normal to reduce the original braking distance from 39 meters to less than 35 meters. Larger rims and larger braking systems are most useful for braking cars with greater inertia, such as large SUVs with high weight, or Ferrari sports cars with a limit speed of more than 300 kilometers per hour.