What is the maximum allowable air leakage rate for a combination vehicle with the engine off and brakes on?

The maximum allowable air leakage rate for a combination vehicle with the engine off and brakes on is 4 psi per minute. This standard is critical for ensuring that the air brake system maintains adequate pressure and functionality, which is vital for safe operation.

A leakage rate above this threshold can indicate a potential issue within the braking system, such as a leak in the lines or components, which could result in diminished braking performance and increase the risk of accidents. Maintaining compliance with this standard helps to ensure the reliability of the air brake system, allowing drivers to operate their vehicles safely and effectively.

Other options exceed the maximum allowable limit, which could compromise the system's efficiency and safety. Recognizing this standard is essential for drivers and vehicle inspectors to maintain vehicle safety and functionality on the roads.