Why is it important to be in the proper gear before starting down a hill?

Being in the proper gear before starting down a hill is crucial primarily because it helps maintain the engine braking effect. When a driver shifts to a lower gear before descending, the engine can act as a brake, slowing the vehicle down more effectively than relying solely on the brake pedal. This is particularly important for heavy vehicles, such as trucks, that can gather significant speed due to their weight and momentum. Utilizing engine braking allows for better control of the vehicle, reducing the risk of overheating the brake system, which can occur if the brakes are used excessively.

In contrast, while better visibility, fuel efficiency, and tire wear are important considerations in driving, they are not the primary reasons for selecting the correct gear when going downhill. Proper gear selection directly contributes to safer and more effective control during a descent, making it a crucial aspect of operating a commercial vehicle in hilly terrain.