Commercial Driver’s License (CDL) Practice Exam 2025 - Free CDL Practice Questions and Study Guide

When preparing to drive in mountainous terrain, it's crucial for a driver to review instructions for the vehicle and understand how altitude affects brake performance. This is especially important because mountain driving presents unique challenges, including steep grades and changes in air pressure that can significantly impact vehicle operation.

At higher altitudes, the thinner air can reduce the effectiveness of the brakes due to less air resistance for braking systems that rely on air pressure. Knowing this, a driver can adjust their driving strategy—such as using lower gears to maintain control on descents and anticipating longer stopping distances. Proper understanding of the vehicle's specifications and performance at different altitudes ensures safer driving practices in these challenging environments.

Other important preparations for mountainous driving may include securing cargo and checking weather conditions, but these actions do not directly address the critical safety aspects regarding vehicle performance that altitude can affect, making the understanding of altitude's impact on brake performance the most pertinent consideration.