When the following four conditions occur, the brake pads should be replaced in time:
1. When the thickness of the brake pads is less than the minimum maintenance standard allowed by the vehicle manufacturer.
2. When the wear alarm switch on the brake pad has been alarmed.
3. When the brake pads are contaminated with oil or grease.
4. When the brake pad has abnormal noise when braking. Under normal circumstances, if the thickness difference between the two sides of the brake caliper on the fixed caliper reaches 1.5mm, the difference between the thickness of the brake lining on the floating caliper reaches 3.0mm, it needs to be replaced.
However, it is not possible to accurately determine whether the brake pads are worn by simple external observation. It is best to use a ruler to measure the thinnest part of the brake pads to see if they are within the allowable range.