You want to drive an agricultural tractor with two trailers equipped with compressed-air brakes. What do you have to ensure you do with the manual brake power regulator on each of the trailers?

You answered correctly. When towing trailers with compressed-air brakes, you must set the manual brake power regulator on each trailer according to the actual load the trailer is carrying. This ensures that the braking force is properly matched to the trailer's weight, preventing dangerous situations such as skidding (if the brakes are set too high for a light load) or too little braking force (if set too low for a heavy load). The tractor's weight or permitted gross weight is not relevant for setting the trailer’s regulator—only the actual current load on each trailer matters. Always check and adjust the setting before driving to ensure safety.