How to Study for the CDL Knowledge Tests

The CDL knowledge tests check what is written in your state’s CDL manual. The most reliable way to prepare is to study that manual directly and use practice questions to find the parts you have not learned yet. This guide gives you a simple plan.

1. Get the current manual from your state

Download the CDL manual from your state licensing agency’s own website, and check its edition date. Avoid copies hosted elsewhere, which can be out of date. Keep it open while you practice so you can check every answer.

2. Work out which tests you need

Everyone takes General Knowledge. The other tests depend on the license class and endorsements you want, for example Air Brakes, Combination Vehicles for a Class A license, or the Hazardous Materials, Tank, Doubles/Triples, Passenger or School Bus endorsements. Your state manual and licensing agency list exactly which tests apply to you. Our guide CDL Classes, Endorsements and Restrictions Explained sums up what the manual says.

3. Know the passing mark

Federal rules require at least 80% correct on each knowledge test (49 CFR 383.135 (eCFR)). Aim higher than that in practice so a few unfamiliar questions on test day do not decide the result. The number of questions varies by state, so check your state’s manual.

4. Study one section at a time

• Read one section of the manual, then practice only that topic.
• In practice mode, read the explanation for every question, including the ones you got right.
• When you miss a question, open the manual section we cite and reread the whole paragraph, not only the quoted phrase.

5. Switch to exam mode

Once you are comfortable with a section, take a full test in exam mode, which hides answers until the end. Review your missed questions by topic and go back to those manual sections before the next attempt.

6. Before test day

• Check your licensing agency’s website for the documents, fees and appointments it requires.
• Reread the sections you missed most often.
• Remember that practice questions, including ours, are not the real test questions. Knowing the manual is what counts.

Sources

• 49 CFR 383.135 (eCFR), knowledge test passing score.
• Your state’s current CDL manual, published by your state licensing agency.