What is the significance of using wheel chocks during air system tests?

Using wheel chocks during air system tests is crucial for ensuring safety by preventing the vehicle from rolling. When performing tests that involve pressure changes or manipulations of the vehicle's components, such as the air system, there is always a risk that the vehicle could move unintentionally. Wheel chocks act as sturdy blocks that secure the wheels in place, thereby ensuring that the vehicle remains stationary during the testing process. This safety measure protects both the operator and any nearby personnel from potential accidents that could occur if the vehicle were to roll.

The other options, while they highlight important aspects of vehicle maintenance and operation, do not pertain directly to the primary function of wheel chocks during air system tests. Enhancing brake performance and securing air leaks relate to the functioning of the braking system itself, while measuring air pressure accurately involves specific gauges and equipment rather than the placement of chocks. Thus, the primary significance of using wheel chocks lies in their role as a safety feature to keep the vehicle stable during inspections or tests.