This depends on the usual road conditions to decide, usually in 5-8 million kilometers to check the bearings. There are also car running up weng weng sound, it is time to change.
Bearings (Bearing) is an important part of contemporary mechanical equipment. Its main function is to support the mechanical rotating body, reduce the friction coefficient (friction coefficient) in the process of its movement, and to ensure its rotary accuracy (accuracy).
Expanded Information
Under a certain load, the bearing in the emergence of pitting before the number of revolutions or hours, known as the bearing life.
The life of a rolling bearing is defined in terms of the number of revolutions (or the number of hours of operation at a given speed): a bearing within this life should experience initial fatigue damage (spalling or chipping) on any of its rings or rolling elements. However, whether in the laboratory test or in actual use, can be clearly seen in the same working conditions of the appearance of the same bearing, the actual life is very different.
In addition, there are several different definitions of bearing "life", one of which is the so-called "working life", which indicates that the actual life of a bearing can be achieved before damage is caused by wear and tear, damage is usually not caused by fatigue, but by wear and tear, corrosion, seal damage and other causes.
In order to determine the standard of bearing life, the bearing life and reliability.
Because of manufacturing precision, material uniformity differences, even if the same material, the same size of the same batch of bearings, used in the same working conditions, the length of its life is not the same. If the statistical life of 1 unit, the longest relative life of 4 units, the shortest 0.1-0.2 units, the longest and shortest life ratio of 20-40 times. 90% of the bearings do not produce pitting corrosion, the number of revolutions or hours experienced is called the rated life of the bearing .
Reference:
Baidu Encyclopedia-Bearings