CDL Written Test Study Guide: Tips to Pass on Your First Try

The CDL written test is your first big step toward becoming a professional truck driver—and it can be intimidating. With dozens of rules, regulations, and safety procedures to memorize, many applicants feel overwhelmed. But with the right strategy, preparation, and mindset, you can pass the CDL written test on your first try.

This guide walks you through everything you need to know to prepare smart, study effectively, and walk into the DMV with confidence.

What Is the CDL Written Test?

The Commercial Driver’s License (CDL) written test is the knowledge portion of the licensing process. It covers topics such as:

  • General driving and safety rules for commercial vehicles

  • Air brakes (if applicable)

  • Combination vehicles (if applying for Class A)

  • Endorsements like hazmat, tankers, doubles/triples, and passenger vehicles

You’ll need to pass the general knowledge test and any other required sections based on the type of CDL and endorsements you’re applying for.

How Many Questions Are on the CDL Written Test?

  • General Knowledge: About 50 questions

  • Air Brakes: About 25 questions

  • Combination Vehicles: About 20–25 questions

  • Each Endorsement: Around 20 questions

Passing scores vary by state but are typically 80% or higher.

Step-by-Step Guide to Passing the CDL Written Test

1. Start with Your State’s CDL Manual

Your state’s CDL handbook is your official study guide. It contains everything the test is based on—including diagrams, definitions, and safety procedures.

Download it from your state DMV’s website or pick up a printed copy at your local DMV office. Read it thoroughly, especially the sections relevant to your license class and endorsements.

2. Break the Material into Sections

Instead of reading the entire manual at once, divide it into smaller parts:

  • General knowledge (everyone needs this)

  • Air brakes (required for most Class A and B drivers)

  • Combination vehicles (for tractor-trailers)

  • Endorsements (hazmat, tanker, passenger, etc.)

Make a study schedule and tackle one section at a time.

3. Use Free CDL Practice Tests

One of the best ways to prepare is by taking online practice tests. These mimic the real DMV exam format and help you get comfortable answering questions under pressure.

Benefits of practice tests:

  • Identify your weak areas

  • Learn how questions are worded

  • Build test-taking confidence

Aim to consistently score 90% or higher on practice tests before taking the real one.

4. Make Flashcards for Memorization

Some parts of the CDL test require you to memorize numbers, definitions, and procedures. Flashcards help you retain information like:

  • Vehicle inspection steps

  • Air brake system components

  • Legal blood alcohol limits

  • Stopping distances

Use physical flashcards or apps like Quizlet to make studying more interactive.

5. Watch CDL Training Videos

If you’re a visual learner, watching CDL prep videos can help you understand complex topics. YouTube has several reliable CDL instructors who explain everything from pre-trip inspections to tricky test questions.

Search for topics like:

  • “CDL general knowledge walkthrough”

  • “Air brakes CDL explained”

  • “Combination vehicles CDL test prep”

6. Get Enough Rest Before Test Day

Being well-rested helps with focus, memory, and reducing test anxiety. Avoid cramming the night before. Instead, do a light review and get at least 7–8 hours of sleep.

7. Take the Test When You’re Ready—Not Rushed

Don’t schedule your test just to “get it over with.” Take it when you feel confident. If you’re still struggling with certain sections, give yourself a few more days of practice.

Being prepared gives you a much better chance of passing on your first try.

Common Mistakes to Avoid

  • Skipping the manual – Even if you do great on practice tests, you need the official handbook to cover all the rules.

  • Only studying general knowledge – If you’re applying for Class A with air brakes, you need to study all 3 sections.

  • Guessing during the test – Read every question and answer choice carefully. Some answers are tricky.

  • Waiting too long between studying and testing – Test while the material is still fresh.

Test Day Tips

  • Bring all required documents (permit application, ID, etc.)

  • Arrive early so you’re not rushed or flustered

  • Read each question twice before answering

  • Eliminate obviously wrong answers if you’re unsure

  • Don’t second-guess yourself unless you’re sure about the change

Final Thoughts

Passing the CDL written test doesn’t have to be stressful. With a structured study plan, the right resources, and enough practice, you can walk in with confidence and walk out with your Commercial Learner’s Permit (CLP).

And once you have your CLP, you’re on your way to the next stage—behind-the-wheel training and your skills test.

Stay focused, stay disciplined, and you’ll be a licensed commercial driver before you know it.