The main parameters of automobile hub are: hub size, PCD, offset ET, center hole.

Hub size consists of two parameters: tyre ring diameter and tyre ring width. Expressions are 15x6.5; 15x6.5JJ; 15x6.5J; 1565 and so on. There are no hard rules in the format. The front "15" denotes the diameter of the tyre ring, which represents a hub of 15 inches, while the rear "6.5" (or 6.5J, 6.5JJ, 65) denotes the width of the tyre ring, which represents a hub of 6.5 inches. Hub dimensions can usually be found on the back of the hub engraving.

PCD: refers to the pitch diameter of hub bolt hole. Expressions such as 5x114.3, 10x100/114.3, "5" means the number of bolt holes, representing five bolt holes. "114.3" indicates that the pitch diameter of bolt hole is 114.3 mm.

Offset: (also known as offset or ET) is the distance between the installation surface and the hub center line, which is usually found on the back of the hub. The offset is used to adjust the wheelbase and ensure that the wheels do not interfere with the body.

Center hole: the big hole in the middle of the hub. Note that the size of the center hole is measured from the back. Every car is different. BENZ is 66.6MM and BMW is 72.6MM. If the axle hole of the wheel ring is large, the middle hole ring must be used, otherwise the wheel will jitter at high speed.