What condition leads to rejection of a vehicle regarding brake rotors?

The condition that leads to the rejection of a vehicle regarding brake rotors is when two or more grooves are worn beyond .090 inch. This specific measurement is significant because the purpose of brake rotors is to provide a smooth surface for brake pads to create friction and stop the vehicle. When grooves are worn deeply, they can significantly impact the efficiency and effectiveness of the braking system.

Deep grooves can lead to uneven wear on brake pads, which in turn can decrease braking performance and increase stopping distances. Furthermore, excessive wear can cause vibration and noise during braking, which are indicators of a failing braking system. Therefore, if the grooves on the brake rotors exceed the specified limit of .090 inch, it is an important safety concern, leading to the rejection of the vehicle during inspection.

In contrast, the other conditions related to brake rotors, such as having only one groove worn or the rotors being damaged without specific measurements of wear, may not necessarily indicate the rotors are beyond safe operational use. Also, while rotors having less than 1/4 inch thickness could be a concern, it is not specifically tied to the precise measurement of groove wear that affects braking efficiency. Thus, the most critical factor for rejection based on this question focuses on the