When driving down a long steep hill, when should you release the brake?

Answer: D — When you are 5 MPH below your safe speed

Releasing the brake when you are 5 MPH below your safe speed is the correct approach when driving down a long steep hill. This technique helps maintain control of the vehicle and prevents brake overheating, which can lead to brake failure. By waiting to resume normal speed until you have slowed down adequately, you ensure that the vehicle remains at a safe speed that is manageable for the incline of the hill. Additionally, this method allows for more effective use of engine braking, keeping you within a safe operating range, and giving you room to react if road conditions or traffic change suddenly. Monitoring your speed and making adjustments at the appropriate times are essential for safe downhill driving in commercial vehicles.