The same diameter, but the width is not the same, with the opposite, but the two different data hub, suitable for different tires. Some people think the original tire is not high enough, want to upgrade, is often widened to reduce the flat ratio, increase the diameter, change the material, this time, if you have to change the hub, called modified hub.
Car wheel hub bearings in the past is the largest single-row tapered roller or ball bearings. As technology has evolved, cars have used car hub units extensively. The use of hub bearing units and the growing use of the third generation has been developed: the first generation of double row angular contact bearings. The second generation on the outer raceway has a flange for the bearing fixed, you can simply set the bearing sleeve to the axle nut. Make car maintenance easy. The third generation of hub bearing unit is the use of bearing units and anti-lock brake system to match. The hub unit is designed with an inner flange and an outer flange bolted to the drive shaft, with the outer flange mounting the entire bearing together.