CDL General Knowledge Study Guide

The General Knowledge test is the foundation of every CDL. Whether you’re pursuing a Class A, Class B, or Class C license, this exam evaluates whether you understand the rules, procedures, and safety practices required to operate a commercial motor vehicle. This study guide breaks the material into manageable sections so you can prepare efficiently.

Vehicle Inspection

Pre-trip inspection is one of the most heavily tested topics. You need to know how to check tires, brakes, lights, coupling devices, cargo securement, and emergency equipment. The manual describes a systematic seven-step inspection process—learn the order and the specific defects to look for at each step.

Examiners often ask about minimum tread depth, how to identify brake adjustment problems, and what constitutes an out-of-service condition. Practice describing inspections out loud as if you were performing a real walk-around.

Basic Vehicle Control

This section covers starting, stopping, turning, and backing a large vehicle. Key concepts include off-tracking (the rear wheels follow a shorter path than the front), the danger of rolling backward on a grade, and proper mirror use. Shifting questions focus on progressive shifting, double-clutching in older transmissions, and knowing when to use lower gears on downgrades.

Seeing, Communicating, and Managing Space

Commercial vehicles have large blind spots called “No-Zones.” You must know where they are and how to check them. Space management questions test your understanding of following distance, merging, and overhead clearance. Remember the formula: one second of following distance for every 10 feet of vehicle length at speeds under 40 mph, plus extra seconds above that speed.

Speed, Night Driving, and Special Conditions

Heavier vehicles need more distance to stop. Questions about total stopping distance, hydroplaning, and driving on ice appear frequently. Night driving topics include headlight use, fatigue management, and adjusting speed when visibility drops.

Accident and Emergency Procedures

Know what to do after an accident: protect the scene, notify authorities, and document details. Fire-related questions cover classes of fire (A, B, C, D) and which extinguisher type to use for each. You should also understand cargo spill response basics and when to evacuate.

Hours of Service and Regulations

Federal hours-of-service rules limit how long you can drive before taking a break. Study the 11-hour driving limit, 14-hour on-duty window, and 60/70-hour weekly limits. Violations carry serious penalties for both drivers and carriers.

How to Study Effectively

Read your state’s CDL manual chapter by chapter, then test yourself immediately after each section. A CDL General Knowledge practice test reinforces what you’ve learned and reveals gaps before test day.

If your vehicle uses air brakes, pair this guide with the CDL Air Brakes practice test to prepare for that required endorsement exam. For the full exam experience across all sections, try a complete CDL practice test. PassCDL gives you unlimited practice—see pricing for plan details.

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This article is for educational purposes only. PassCDL is not affiliated with any state DMV or licensing agency.