At what thickness must a brake lining be replaced?

Answer: D — 6.4 mm

The correct thickness at which a brake lining must be replaced is 6.4 mm. This specification is essential for maintaining the effectiveness and safety of the braking system. Brake linings that wear down to this thickness may not provide sufficient friction to stop the vehicle safely, especially under heavy braking conditions. Replacing the brake lining at this threshold helps ensure that drivers have optimal stopping power and reduces the risk of brake failure. Utilizing brake components that are too worn can lead to longer stopping distances and increase the risk of accidents. Therefore, regular inspections and timely replacements according to this standard play a crucial role in vehicle safety and maintenance.