If you search for “Free CDL Practice Test” on Google, you will find millions of results. But here is the dirty secret of the industry: most free tests are outdated and dangerous.
In 2022, the federal government implemented the ELDT (Entry-Level Driver Training) mandate. In 2023 and 2024, many states adopted the “Modernized” Skills Test protocol. If you are studying a free question bank scraped from a 2018 manual, you are memorizing wrong answers. You might learn the old “100-point pre-trip inspection” instead of the current “Critical Safety Items” checklist.
This page is a free CDL practice test with verified 2026 questions across the three core written exams every Class A applicant must pass: General Knowledge, Air Brakes, and Combination Vehicles. Every question includes a full explanation of the rule behind it - not just the letter of the correct answer.
For deeper practice on individual subjects, use our dedicated pages:
- CDL General Knowledge Practice Test - 50+ questions focused on Section 2 of the CDL manual
- CDL Air Brakes Practice Test - PSI values, L.A.B. leak tests, and system components
- CDL Combination Vehicles Practice Test - Coupling, fifth wheel, and trailer physics
What You Need to Pass: The Three Written Tests
Before you sit down at the DMV computer, you need to know which tests you are taking and what they cover.
General Knowledge (50 Questions, 80% to Pass)
The longest and broadest test. Covers vehicle inspection, basic control, shifting, space management, night driving, hazard perception, accident procedures, and cargo securement. Applies to all CDL classes (A, B, and C).
Air Brakes (25 Questions, 80% to Pass)
Tests your understanding of pneumatic braking systems: air compressors, reservoirs, brake chambers, slack adjusters, S-cams, and the dual air system. If you fail this test, you receive an L restriction on your CDL and cannot operate any vehicle with air brakes - which eliminates almost all Class A semi-trucks.
Combination Vehicles (20 Questions, 80% to Pass)
Required only for Class A. Covers the physics of pulling a trailer: coupling and uncoupling procedures, the fifth wheel, glad hands, trailer air supply, and the “crack the whip” effect that causes rollovers.
Passing all three gives you a Commercial Learner’s Permit (CLP). You need the CLP before you can begin behind-the-wheel training or take the skills test.
General Knowledge Practice Questions
The questions below cover the most frequently tested topics on the General Knowledge exam. Read each explanation carefully - the DMV changes the numbers and wording between versions.
The formula for following distance is 1 second for every 10 feet of vehicle length when traveling under 40 mph. 40 feet / 10 = 4 seconds. If you were traveling over 40 mph, add 1 extra second (total 5 seconds). This speed threshold is a common trap on the exam.
No matter how many mirrors you have, there are always areas around your truck (directly behind and close to the sides) that you cannot see. This is why "Get Out And Look" (G.O.A.L.) is the standard procedure for backing. Why A is wrong: you should check mirrors every 5 to 8 seconds, not 12 to 15. The 12 to 15 second rule refers to how far ahead you should look down the road, not mirror check frequency.
Heavy trucks have massive torque at idle. You should release the clutch slowly without giving it throttle to engage the gears smoothly. Applying throttle while releasing the clutch can cause the truck to lurch, potentially damaging the driveshaft or causing a jackknife if the trailer is loaded.
Hydroplaning happens when your tires ride on top of water instead of the road surface. The correct response is to release the accelerator and push in the clutch to let the vehicle slow naturally. Do not brake - braking can cause a skid. Do not steer sharply - you could lose control entirely.
At highway speeds, 12 to 15 seconds equals about one quarter mile ahead. This gives you time to identify hazards, plan lane changes, and react to stopped traffic. At lower speeds in city traffic, you should still look at least one block ahead.
For more questions on this section, take our full CDL General Knowledge Practice Test.
Air Brakes Practice Questions
Air brake questions are heavily numerical. The DMV wants to see that you have memorized the exact PSI values. Missing a single number can cost you the question.
Do not confuse the "Supply Pressure Gauge" (which shows tank air, typically 100 to 125 PSI) with the "Application Pressure Gauge." The application gauge only moves when you press the brake pedal. It tells you how much air pressure you are sending to the brake chambers.
A dual air system separates the front and rear brake circuits for redundancy. If one circuit fails, you still have partial braking, but your stopping distance increases dramatically and the system is compromised. It is illegal and unsafe to continue driving. Stop immediately.
This is a pure memorization trap. The four values you must know: * Straight Truck (Static / foot off brake): 2 psi in one minute * Combination Vehicle (Static / foot off brake): 3 psi in one minute * Straight Truck (Applied / foot on brake): 3 psi in one minute * Combination Vehicle (Applied / foot on brake): 4 psi in one minute
The low air pressure warning device must activate before the air pressure drops below 60 PSI. In practice, most trucks are set to trigger the buzzer and warning light between 55 and 60 PSI. If you hear that buzzer during driving, pull over immediately.
Spring brakes are a failsafe. A heavy coil spring holds the brakes in the applied position. Air pressure holds the spring compressed during normal driving. If air pressure is lost (line rupture, compressor failure), the spring releases and applies the brakes automatically. This is why a truck with no air pressure has its brakes locked on - the springs are doing their job.
For more air brake questions, see our full CDL Air Brakes Practice Test.
Combination Vehicles Practice Questions
Combination vehicle questions test your knowledge of the coupling system and the unique physics of pulling a trailer.
When air rushes out of the broken lines, the Tractor Protection Valve detects the pressure drop and snaps shut (typically between 20 and 45 PSI). This seals off the tractor's air supply so you still have air to steer and brake the truck to a controlled stop. The trailer's emergency spring brakes apply automatically because it lost air pressure.
You stop when the fifth wheel contacts the trailer apron plate. Then get out and visually verify the trailer height is correct - the apron should sit flat on the fifth wheel, not above it (high hookup) or below it. Backing straight into the kingpin without checking height can damage the fifth wheel or cause a failed coupling.
A jackknife occurs when the trailer's rear wheels lose traction (lock up from heavy braking or hit ice) and the trailer swings out of alignment with the tractor. The trailer pivots around the fifth wheel like a folding knife. To prevent jackknifing: brake gradually, avoid sudden steering corrections, and be especially careful in wet or icy conditions.
Inspect the rubber seals on both glad hands before connecting. Dirt, cracks, or missing seals cause air leaks that will fail your leak test. The blue (service) line connects to the blue glad hand and the red (emergency) line connects to the red glad hand. Make sure the locking collars click into place.
For the complete coupling checklist and more trailer questions, use our CDL Combination Vehicles Practice Test.
How to Score Yourself
Count your correct answers out of 14 above:
- 13-14 correct (93-100%): You are ready. Move on to the full practice tests for each subject.
- 11-12 correct (79-86%): Almost there. Review the questions you missed and re-read the relevant sections of the CDL manual.
- 9-10 correct (64-71%): Not yet. Focus on your weakest section before retaking.
- Below 9 (under 64%): You need more study time. Read the full CDL manual chapters before attempting more practice tests.
The DMV passing threshold is 80%. But on any practice test at home, you should aim for 90% or higher. Test-day nerves, time pressure, and different question wording will typically cost you 5 to 10 percentage points.
Study Strategy: How to Use Free Practice Tests Effectively
Taking a practice test once is not a study plan. Here is the method that produces results:
Step 1: Take a diagnostic test cold. Do not study first. Use the questions above as your baseline. Write down which sections you missed (General Knowledge, Air Brakes, or Combination). This tells you where to focus your reading time.
Step 2: Read the CDL manual with purpose. Do not read cover to cover. Go straight to the sections where you scored worst. The CDL manual is organized by test: Section 2 is General Knowledge, Section 5 is Air Brakes, Section 6 is Combination Vehicles. Read only the sections you need.
Step 3: Take subject-specific practice tests. Use our dedicated pages for deep practice:
- General Knowledge Practice Test - the longest and most important test
- Air Brakes Practice Test - memorize the PSI numbers
- Combination Vehicles Practice Test - coupling and trailer physics
Step 4: Review every wrong answer. The learning happens after the test, not during it. Read the explanation. Go back to the manual for that specific topic. Understand the rule, not just the answer.
Step 5: Retake until you hit 90% on two consecutive attempts. Consistency matters more than a single high score. If you score 95% once and 70% the next time, you are not ready. You need reliable knowledge, not lucky guessing.
Why Outdated Practice Tests Fail You
Many students download free PDFs of “500 CDL Questions” from random websites. Here is why that strategy gets people killed on the real exam:
- Passive reading vs active recall: Reading a list of answers is passive. You nod along and think you know it. But when the exam computer shows you a question with slightly different numbers, you freeze. Interactive practice forces you to make a decision, which builds actual memory.
- No explanations: Knowing “C is correct” is worthless if you do not know why. The DMV randomizes question pools and changes numbers between test versions. If you only memorized the letter, you will fail when the test changes “40-foot vehicle at 35 mph” to “50-foot vehicle at 45 mph.”
- Pre-2022 content: The ELDT mandate changed what the DMV tests you on. Outdated question banks may include questions about topics that are no longer tested, and miss questions about topics that were added. Always verify that your practice test source was updated for 2026.
What to Do After You Pass the Written Tests
Getting your CLP is step one. Here is what comes next:
- Schedule your ELDT training. You must complete behind-the-wheel training through a provider on the FMCSA Training Provider Registry. See our guide on how to get a CDL without going to school for low-cost options.
- Pass the three-part skills test. Vehicle inspection, basic controls (backing maneuvers), and the road test. Practice pre-trip inspection until you can do it in your sleep.
- Get your endorsements. HazMat, Tanker, Doubles/Triples - these unlock the highest-paying jobs. Start with our CDL HazMat Study Guide to understand the TSA background check process (it takes 30 to 45 days, so start early).
Conclusion
A free CDL practice test is only useful if the questions are current and the explanations teach you the underlying rules. Use the 14 questions above as your diagnostic. Find your weak sections. Then dive into the subject-specific practice tests for General Knowledge, Air Brakes, and Combination Vehicles.
Do not walk into the DMV until you can score 90% on two consecutive practice tests. The written exam is the easiest part of the CDL process - if you fail it, the skills test will destroy you. Study now, pass once, and start driving.
Frequently Asked Questions (FAQ)
How many questions are on the CDL permit test?
The CDL General Knowledge test has 50 questions and you need 80% (40 correct) to pass. The Air Brakes test has 25 questions (20 correct to pass). The Combination Vehicles test has 20 questions (16 correct to pass). You must pass all three to receive a Class A Commercial Learner’s Permit.
Are free CDL practice tests accurate for 2026?
Many are not. Free websites often use question banks scraped from pre-2022 manuals that do not reflect ELDT mandate changes, updated Human Trafficking awareness requirements, or Modernized Skills Test protocols. Always check the “Last Updated” date and cross-reference with the current official CDL manual from your state DMV.
What is the passing score for the CDL permit test?
The passing score for all CDL written knowledge tests is 80%. For the General Knowledge test, that means 40 out of 50 correct answers. For Air Brakes, 20 out of 25. For Combination Vehicles, 16 out of 20. On any practice test at home, aim for 90% or higher before scheduling your DMV appointment.
Can I take the CDL permit test online?
In most states, no. CDL knowledge tests must be taken in person at a DMV or driver license office on a computer kiosk. A few states allow online testing for the Commercial Learner’s Permit, but you must check with your specific state DMV for current rules. The skills test (vehicle inspection, backing, road test) must always be taken in person.
What should I study first for the CDL permit test?
Start with General Knowledge. It is the foundation that all other CDL tests build on. Read Sections 1 through 3 of your state CDL manual, focusing on driving safely, vehicle inspection, and cargo securement. Take a practice test to identify your weak areas, then study those specific topics before moving on to Air Brakes and Combination Vehicles.