Before descending a long, steep grade in a modern truck you have not driven before, which gear should you select?
Correct answer: A – A lower gear than the truck might need to climb the same grade
Modern trucks may climb grades in relatively high gears because of powerful engines, low-friction components, and aerodynamic designs. Those features provide less resistance during a descent, so a lower gear may be necessary downhill than uphill. Select the proper low gear before beginning the descent and use engine braking as the primary means of controlling speed.
Source: Washington State Commercial Driver Guide — § 2.16.2, “Select the Right Gear Before Starting Down the Grade”

