What are the maximum allowable leakage rates for single vehicles?

Answer: B — Less than 2 PSI in one minute

The maximum allowable leakage rate for single vehicles is correctly identified as less than 2 PSI in one minute. This standard is important for ensuring that the air brake system is functioning properly and that the vehicle can stop safely. A leakage rate above this threshold could indicate a potential issue with the air brake system, which may lead to decreased braking effectiveness and increased stopping distances, putting the driver and others on the road at risk. The regulation sets this limit to ensure that air brakes maintain adequate pressure for reliable operation. A leakage rate of 2 PSI or less in one minute suggests the system is sufficiently sealed and in good working order, which is crucial for safety. The focus on maintaining the brakes within this threshold emphasizes the importance of regular system checks to prevent brake failure due to air loss.