The CDL General Knowledge test is required for every CDL applicant regardless of the vehicle class or endorsements you're pursuing. Here's a comprehensive breakdown of what to expect and how to prepare.
Test Format
- Questions: 50 multiple-choice questions
- Passing score: 80% (40 out of 50 correct)
- Time limit: Varies by state (typically 60–90 minutes)
- Attempts: Most states allow retakes after a waiting period
Major Topic Areas
1. Vehicle Inspection (Pre-Trip)
Know the seven-step inspection method. You'll be tested on what to check under the hood, on the engine compartment, the cab interior, lights, mirrors, tires, brakes, and coupling systems.
2. Basic Vehicle Control
Understand how to manage a large vehicle's speed, braking distance, turning radius, and backing. Questions cover the physics of why large vehicles behave differently than cars — especially stopping distance.
3. Shifting and Backing
Proper shifting technique, double-clutching, when to upshift/downshift, and safe backing procedures are common test topics.
4. Coupling and Uncoupling
The steps for safely coupling a tractor to a trailer and uncoupling it appear frequently in the General Knowledge test, especially for Class A applicants.
5. Pre-Trip Inspection
Understand what constitutes a "defect" that makes a vehicle unsafe to drive, what items must be checked before every trip, and what information must be in the vehicle at all times.
6. Basic Hazardous Materials Rules
Even without a HazMat endorsement, you need to know basic rules — like when hazmat placards are required and what the driver's responsibilities are when transporting regulated materials.
7. Transporting Cargo Safely
Weight limits, load securement, preventing cargo shifts, and handling oversized loads are tested in this section.
8. Driving Safely
Speed management, managing space around the vehicle, night driving, driving in adverse conditions, and emergency maneuvers.
Study Strategy
- Read the General Knowledge section of your state's CDL manual at least once
- Take practice tests to identify weak areas
- Focus extra time on stopping distances and pre-trip inspection — these are the most commonly missed topics
- Take the practice test again the day before your appointment
Common Mistakes to Avoid
- Confusing stopping distance rules — always account for both perception time and braking distance
- Missing questions about cargo securement requirements
- Overlooking the basic HazMat rules included in General Knowledge