How to Pass the CDL Exam: Top Study Tips for Knowledge & Skills Tests

Passing the CDL exam is the gateway to one of the most in-demand careers in North America. But many candidates fail on their first attempt — not because the material is too difficult, but because they underestimate the knowledge tests, skip the right study resources, or don’t understand the exam structure. This guide gives you a proven study framework to pass the CDL knowledge and skills tests efficiently.

Understanding the CDL Exam Structure

The CDL licensing process in the United States consists of two phases: knowledge tests (written, taken at the DMV to obtain your Commercial Learner’s Permit) and skills tests (conducted in an actual CMV after your ELDT training). Knowing what each phase covers lets you study the right material.

CDL Knowledge Tests

Every CDL applicant must pass a General Knowledge test (50 questions, 80% passing score in most states). Class A applicants must additionally pass the Combination Vehicles test. Depending on the endorsements you seek, you’ll also need to pass one or more endorsement tests:

H — Hazardous Materials: 30 questions (plus a TSA background check and fingerprinting)
N — Tank Vehicles: 20 questions
T — Double/Triple Trailers: 20 questions
P — Passenger Vehicles: 20 questions
S — School Bus: 20 questions
X — Combination Tanker/Hazmat: Combined H + N test

All CDL knowledge tests are based directly on your state’s CDL Driver Handbook, which in turn is based on the FMCSA’s CDL Testing Standards. Every single question on the test can be found by reading your state handbook thoroughly.

CDL Skills Test

The skills test has three parts, conducted in a CMV appropriate for the class you’re testing for:

Pre-Trip Vehicle Inspection: You must demonstrate that you can inspect the vehicle and identify safety defects. Examiners expect you to walk through the inspection verbally and physically — covering engine compartment, cab, lights, tires, brakes, coupling system, and trailer.
Basic Vehicle Control: A series of maneuvers on a closed course — typically straight-line backing, offset backing (left and/or right), and parallel parking or alley docking.
On-Road Driving: Approximately 30–60 minutes of actual road driving, evaluated on lane control, intersections, railroad crossings, curves, and hazard awareness.

The 6-Step Study Framework

Step 1: Download Your State’s CDL Handbook — And Actually Read It

Every state DMV publishes a free CDL handbook (sometimes called the Commercial Driver License Manual). This is the only primary source for knowledge test questions. Download the PDF or pick up a print copy. Read it end to end before doing anything else. Most candidates underestimate how much detail is in the handbook and fail because they skipped sections.

Step 2: Use Practice Tests — But from the Right Sources

After reading the handbook, use practice tests to identify your weak sections. Focus on state-specific practice test banks that are updated to match current FMCSA testing standards. Take each section test (General Knowledge, Air Brakes, Combination Vehicles, and any endorsement tests you need) at least 3–5 times until you consistently score 90%+. Aiming only for the 80% passing score leaves you too little margin for unfamiliar question phrasing on the real test.

Step 3: Master the Air Brakes Section Separately

If you will be operating a vehicle with air brakes (as most Class A drivers will), the Air Brakes knowledge test is one of the most commonly failed sections. The material is dense and technical. Study it as a standalone module. Key concepts to master: the dual air brake system, air brake adjustment limits, braking distance calculations, proper use of the parking brake, and the low air pressure warning signals.

Step 4: Memorize the Pre-Trip Inspection Sequence

The pre-trip inspection is a checklist of roughly 40–60 items conducted in a specific sequence. Most CDL training schools use a standardized walk-around sequence (engine compartment → front of cab → driver’s side → rear → passenger side → inside cab). Practice this verbally out loud until it is automatic. Many skills test failures come from omitting inspection steps that were memorized but not practiced physically.

Step 5: Log Backing Hours Before Your Skills Test

Backing maneuvers — particularly offset backing and parallel parking — are where most skills test candidates earn penalty points or exceed their pull-up allotment. Your ELDT school will provide backing practice time, but supplement it with as many additional hours as you can arrange in a practice yard. Backing is a feel skill that only repetition builds.

Step 6: Treat the Road Test Like a Job Interview

Examiners are looking for safe, predictable, professional driving. That means: smooth and deliberate steering inputs, complete stops at every stop sign and red light, proper mirror scanning (every 5–8 seconds), lane position discipline, proper use of turn signals well in advance, and controlled speed. Avoid the temptation to “show off” by driving faster or more aggressively than necessary.

Common Reasons CDL Candidates Fail

Skipping the Air Brakes section of the handbook
Not reading the full handbook before taking practice tests
Insufficient backing practice before the skills test
Rushing through the pre-trip inspection and omitting items
Nervousness on the road test causing missed mirrors and incomplete stops

Frequently Asked Questions

How many times can you fail the CDL knowledge test?

This varies by state. Most states allow 3 attempts before requiring a waiting period or mandatory retesting fee. Some states require you to wait 7 days between attempts. Check your specific state DMV policy before scheduling your first attempt.

Do I need to attend a CDL school, or can I self-study?

Since the FMCSA’s Entry-Level Driver Training (ELDT) rule took effect on February 7, 2022, first-time Class A and Class B CDL applicants in the US must complete training at an FMCSA-registered Training Provider Registry (TPR) school. Self-study alone is no longer sufficient for skills training, though you can self-study for the knowledge tests. Canadian requirements vary by province.

About the Author

Marcus Reid is a former OTR driver and CDL training instructor with 18 years of industry experience. → Back to the CDL Training & Trucking Careers Center

Sources

Disclaimer: CDL licensing requirements, passing scores, and procedures vary by state and are subject to change. Always verify current requirements directly with your state’s DMV or motor vehicle authority.

How to Pass the CDL Exam: Top Study Tips