Usually 5.5J, 6J, 7J said unit inches, the tire is usually installed 185 tires need 5-inch rim width, 195 need 6-inch, 205 need 6.5-inch 215 tire width you need to correspond to 7-inch wide Rims.
12, 13, 14, 15 and other specifications, the unit is inch, currently available vehicles have 20-inch wheels equipped models, such as the Infiniti FX35, BMW X5 and so on.
That is, the diameter of the circle formed by the tire screw is in mm, the domestic car is usually 100,114.3, and the European car is special, including 98 in the Love Express, 108 in the Volvo, 120 in the BMW and 112 in M. Benz.
This ensures that the geometric center of the rim coincides with the geometric center of the hub. As a result, the steering wheel will not shake when the vehicle is running at high speeds.
Geometric center line:
The most important reference data for the rim, including the calculation of the Offset value, the net distance from the leaf, etc., must be referenced.
The most important effect of the distance between the hub fixing surface and the geometric center line is to ensure that the tire will not rub onto the bodywork.
Used to support the tire tread, and absorb the impact from the road.
Tightly bonded to the tire bead to provide good air tightness to establish tire pressure.
Some of the rims of the rims protrude beyond the vertical line of the plate so that the rims can not be protected by the tire. A slight careless parking may damage the rims.
Modified multi-piston calipers must consider the data, or there may be friction between the rim disc and brake calipers