When should you check the air pressure in your combination vehicle's system?

Answer: C — Before you start your journey

Checking the air pressure in your combination vehicle's system before starting your journey is critical for ensuring safety and optimal performance. Proper air pressure is essential for the braking system, which relies on compressed air to function effectively. If the air pressure is too low, the brakes may not engage properly, increasing the risk of accidents. Conducting this check before you hit the road helps identify any issues with the air system that could compromise your vehicle's safety. It allows for timely repairs or adjustments to be made, ensuring that all components are functioning within the required parameters. This proactive measure is a fundamental part of pre-trip inspections mandated for commercial drivers to promote road safety and compliance with regulations.