Which of the following is NOT one of the air brake tests performed during a pre-trip inspection?

The performance stop test is not one of the standard air brake tests conducted during a pre-trip inspection. The purpose of the pre-trip inspection is to ensure that all safety systems, including air brakes, are functioning correctly before operating the vehicle. The air leak test evaluates the integrity of the air brake system by checking for leaks, ensuring that air pressure can be maintained. The low air warning test checks if the warning system activates when air pressure drops to a predetermined level, providing an alert to the driver. The emergency stop test is essential for confirming that the brakes engage properly in the event of a loss of air pressure.

In contrast, the performance stop test is generally associated with assessing how well the vehicle can stop under normal operating conditions but does not specifically fall under the usual air brake inspection procedures. Therefore, it is not included in the list of required air brake tests during a pre-trip inspection.