Why is it important to be in the proper gear before starting downhill?

Being in the proper gear before starting downhill is crucial for safety and vehicle control, specifically to prevent the tractor from gaining excess speed. When descending a hill, relying solely on brakes can lead to brake overheating and potential failure, putting the driver and others on the road at risk. By selecting a lower gear, the engine can help slow the vehicle through engine braking, which slows down the vehicle more effectively and stabilizes its descent. This combination of gear selection and engine braking manages speed more reliably and enhances the driver's ability to navigate downhill sections safely, reducing the likelihood of losing control due to excessive speed.