In order to drive safely on a grade, you will need to use a lower gear when driving in the mountains. What does NOT influence your choice of gear?

Your vehicle’s speed will increase on downgrades because of gravity. Your most important objective is to select and maintain a speed that is not too fast for the:
• Total weight of the vehicle and cargo.
• Length of the grade.
• Steepness of the grade.
• Road conditions.
• Weather.
[California Commercial Driver Handbook]