Free practice test
Free CDL Practice Test
Take our free CDL practice test with 20 questions covering general knowledge, air brakes, and combination vehicles. Instant scoring with explanations.
- 100% free to practice
- No signup required
- State-specific content
This free CDL practice test includes 20 multiple-choice questions drawn from the subject areas covered on the CDL general knowledge test, air brakes test, and combination vehicles test. Topics include vehicle inspection, air brake system components and checks, coupling and uncoupling procedures, and driver qualification requirements.
After you submit, you will see your score, the correct answer for each question, and a plain-English explanation. Use missed questions to identify the areas you need to review before your exam.
These questions are for study practice only and are not official exam questions. ExamsLib is not an official licensing or certification authority. Passing this practice test does not guarantee a passing score on any exam.
These questions are for study practice only and are not official exam questions.
Question 1
Question 2
A driver is convicted of a DUI while operating their personal vehicle, not a commercial motor vehicle. Does this affect their CDL?
Question 3
A driver holding only a CLP is asked to haul a load containing hazardous materials. What is the correct response?
Question 4
Why should air tanks be drained regularly?
Question 5
What should a driver do if the low air pressure warning activates while driving?
Question 6
Why do air brake systems generally use compressed air instead of hydraulic fluid on heavy commercial vehicles?
Question 7
What should a driver do to verify the fifth wheel connection is secure during a pre-trip or coupling check?
Question 8
What blood alcohol concentration (BAC) is the disqualifying threshold for a driver operating a commercial motor vehicle under federal rules?
Question 9
What is the purpose of the spring brakes (parking brake) found on most air brake vehicles?
Question 10
What is a 'combination vehicle' in the context of CDL classifications?
Question 11
What is the 'fifth wheel' on a tractor-trailer combination?
Question 12
What is the purpose of using turn signals well before a turn or lane change?
Question 13
What should a driver do with headlights when driving at night to reduce risk?
Question 14
What is a common effect of driver fatigue?
Question 15
What does the 'X' endorsement on a CDL represent?
Question 16
What does restriction code 'K' mean on a CDL?
Question 17
What should a driver do during the pre-trip inspection to check for air leaks in the system?
Question 18
A driver notices the air pressure gauge is reading below the normal operating range but above the low air warning threshold. What is the safest response?
Question 19
What is the relationship between the air brake restriction on a CDL and the skills test vehicle used?
Question 20
What does the 'P' endorsement on a CDL allow?
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Frequently asked questions
What topics does this CDL practice test cover?
The practice test covers general knowledge topics such as vehicle inspection and driver qualifications, air brake system components and brake check procedures, and combination vehicle topics such as coupling, uncoupling, and the fifth wheel.
Is this practice test the same as the real CDL knowledge test?
No. These questions are for study practice only and are not official exam questions. The real CDL knowledge test is administered by your state's driver licensing agency or its approved testing provider. ExamsLib is not an official licensing authority.
How many questions are on the real CDL general knowledge test?
It varies by state. Most states use 50 questions, but Illinois uses 30 and Pennsylvania uses 70 for Class A (50 for Class B or C). The federal passing score is 80 percent everywhere. Confirm the current format with your state's driver licensing agency before your exam.
Do I need an account to take this practice test?
No account or login is required. The practice test is completely free and your results are saved locally in your browser.
