When should brake rotors be replaced?

Brake rotors should be replaced if they are cracked or worn below the minimum thickness specification. This is crucial for maintaining safe braking performance. When rotors become cracked, their structural integrity is compromised, which can lead to catastrophic failure during operation. Similarly, if the rotors wear down to below the manufacturer's specified minimum thickness, they may not provide the necessary surface for the brake pads to grip effectively. This can lead to increased stopping distances and potential brake failure, posing a serious safety risk.

In contrast, rust on rotors is common and can often be cleaned or may wear off after the brakes are used. Surface scratches may not necessarily indicate a need for replacement unless they are deep enough to affect braking performance. Discoloration, such as bluing from excessive heat, can indicate overheating, but does not automatically necessitate replacing the rotors unless other damage is present. Thus, assessing the condition and specifications of the rotors is key to determining when replacement is necessary.