What are the maximum allowed leakage rates for single vehicles?

Answer: C — 2 psi in a minute

The maximum allowed leakage rate for single vehicles is set at 2 psi in one minute. This standard is crucial for ensuring the safety and efficiency of the vehicle's braking system. A lower leakage rate indicates a healthy air brake system that maintains pressure effectively, which is essential for the proper functioning of brakes in a vehicle. If a vehicle were to exceed this leakage rate, it would suggest potential issues within the braking system, such as leaks in the air lines or malfunctioning components. Keeping the leakage rate at or below this specified maximum helps to ensure that drivers can rely on their brakes fully when needed, thus enhancing overall road safety.