2026 CDL General Knowledge Practice Test | Free Questions for Class A/B/C Permit

Q: How many questions are on the CDL General Knowledge test?

The CDL General Knowledge test commonly contains 50 multiple-choice questions in many states. Your state may use a different number of questions.

Q: What is the passing score for the CDL General Knowledge test?

A passing score of 80% is commonly used by many states, but requirements vary by state.

Q: Is the CDL General Knowledge test hard?

It can be challenging for applicants without prior commercial driving experience, since it covers a lot of specific regulations involving weights, distances, and pressure values. However, with consistent practice using real test questions, most people pass on their first try.

Q: Can I take the CDL permit test in a language other than English?

Some states may offer CDL knowledge testing in languages other than English. Language options vary by state and may differ by test type, so applicants should confirm available languages with their state licensing agency.

Q: How many times can I retake the CDL knowledge test if I fail?

Policies vary by state. Most states allow up to 3 attempts within a set time period. After failing, you can usually retest as soon as the next business day after paying a small retest fee.

What Is the CDL General Knowledge Test?

The CDL General Knowledge test is the foundational written exam that every commercial driver's license applicant in the United States must pass. Under regulations set by the Federal Motor Carrier Safety Administration (FMCSA) and each state's DMV or BMV, this test is a required step toward obtaining your Commercial Learner's Permit (CLP) — regardless of whether you're pursuing a Class A license for tractor-trailers, a Class B license for dump trucks and cement mixers, or a Class C license for passenger vans and small buses.

What Topics Does the CDL General Knowledge Test Cover?

The CDL General Knowledge permit test covers a wide range of safety-critical topics. Here are the five core subject areas you'll be tested on:

1. Vehicle Inspection

Commercial vehicles require mandatory safety inspections before, during, and after every trip. The test focuses on identifying defects in critical components — including play in the steering linkage, tire leaks, cracks in front suspension parts, and the integrity of air brake lines.

2. Safe Driving

This section covers speed management, following distance, looking far ahead, and hazard recognition. Key concepts include slowing down by one-third to one-half in adverse weather like fog or heavy rain, identifying blind spots around a large truck, and using mirrors frequently to monitor surrounding traffic.

3. Cargo Handling

How you load and secure cargo directly affects your truck's stability at highway speeds. Test questions cover GVWR limits and weight distribution. According to the CDL Handbook: you must inspect cargo and securement devices within the first 50 miles, then again every 3 hours or 150 miles — whichever comes first — and after any change in duty status.

4. Railroad Crossings

Railroad crossings present unique hazards for large commercial vehicles. Test questions focus on the specific rules for different vehicle types. For example, school buses and vehicles carrying hazardous materials (placarded HazMat loads) must come to a complete stop between 15 and 50 feet from the nearest rail, turn on hazard lights, and roll down the window to look and listen before crossing.

5. Night Driving

Reduced visibility and driver fatigue make nighttime driving significantly more dangerous. This section tests your knowledge of headlight dimming distances. Under federal standards: dim your high beams within 500 feet of an oncoming vehicle, and within 350 feet when following another vehicle. Questions also cover how to handle glare from oncoming high beams and the concept of "overdriving your headlights."

The 3 Most Commonly Missed CDL General Knowledge Questions

Based on CDL instructor feedback and applicant reports, certain topics trip up first-time test-takers — especially those without prior truck driving experience. Here are the three questions that cause the most trouble:

Front Tire Blowout: Many people's first instinct is to hit the brakes hard — but that's wrong. The correct response is to keep a firm grip on the steering wheel, stay off the brakes, and gradually ease off the accelerator once the vehicle stabilizes.
Brake Fade: Continuously riding the brakes on a long downgrade overheats the drums and causes brake fade. You must downshift to a lower gear and use the "snub braking" technique instead of riding the brakes.
Railroad Crossing Rules: Applicants often miss the specific vehicle types — school buses and placarded HazMat vehicles — that are legally required to stop completely 15–50 feet from the nearest rail and roll down their windows before crossing.

CDL General Knowledge Practice Questions

Here are 10 questions that appear frequently on the actual CDL General Knowledge permit test. Study the explanations carefully — they reflect how the real exam tests each concept:

Q1: When backing a truck, you should:

A. Rely entirely on your mirrors.

B. Look at your path and use a helper whenever possible. ✓ Correct Answer

C. Back up as quickly as possible to avoid blocking traffic.

Explanation: Backing is one of the most dangerous maneuvers in commercial driving. The CDL Handbook says you should always get out and look (G.O.A.L.) before backing, and use a helper outside the vehicle whenever possible. Never rely on mirrors alone.

Q2: As part of your vehicle inspection, what is the critical steering system defect to look out for?

A. Missing nuts, bolts, or cotter keys on steering linkage. ✓ Correct Answer

B. Steering wheel play of less than 10 degrees.

C. Too much grease on the steering knuckles.

Explanation: Any missing or loose nuts, bolts, or cotter keys in the steering linkage can cause catastrophic loss of steering control at highway speeds.

Q3: If a front tire blows out at high speed, your first reaction should be to:

A. Slam on the brakes immediately.

B. Stay off the brakes and grip the steering wheel firmly. ✓ Correct Answer

C. Turn the steering wheel sharply towards the side of the blowout.

Explanation: Hitting the brakes during a front tire blowout increases the risk of a dangerous swerve or rollover. The correct response is to hold the wheel firmly, keep the vehicle straight, and gradually ease off the gas until the vehicle slows to a safe speed before carefully pulling over.

Q4: Under CDL rules, how often must you inspect your cargo securement?

A. Every 50 miles or 150 miles.

B. At every state line crossing.

C. Within the first 50 miles, and then every 3 hours or 150 miles. ✓ Correct Answer

Explanation: This is one of the most tested numbers on the CDL exam. Cargo shifts during transit, so federal safety regulations require an inspection within the first 50 miles, then every 3 hours or 150 miles — whichever comes first — for the rest of the trip.

Q5: What is the proper way to use "Snub Braking" when going down a long, steep downgrade?

A. Apply brakes hard enough to feel a definite slowdown, reduce speed to 5 mph below your safe speed, then release. ✓ Correct Answer

B. Lightly coast on the brakes continuously to maintain a steady speed.

C. Pump the brakes rapidly up and down to keep the drums cool.

Explanation: Riding the brakes continuously on a downgrade overheats the drums and causes brake fade — a total loss of braking power. With snub braking, you apply firm pressure to slow the vehicle to 5 mph below your target speed, then fully release the brakes to let them cool before repeating the cycle.

Q6: You are driving in heavy rain. When can hydroplaning occur?

A. Only when your commercial truck is fully loaded.

B. At speeds as low as 30 mph when water builds up on the road. ✓ Correct Answer

C. Only if your tires are brand new and have deep tread.

Explanation: Hydroplaning happens when a layer of water builds up between your tires and the road surface, causing you to lose traction and steering control. If water is deep or tires are worn, it can happen at speeds as low as 30 mph.

Q7: Which of these vehicles must stop completely before crossing any railroad tracks?

A. Empty flatbed trailer trucks.

B. Double-trailer combination transport units.

C. School buses and vehicles carrying hazardous materials (HazMat). ✓ Correct Answer

Explanation: Federal regulations require all school buses and placarded HazMat vehicles to stop completely between 15 and 50 feet from the nearest rail at every railroad crossing — even if no warning signals are active.

Q8: What does "overdriving your headlights" mean during night driving?

A. Driving with faulty or flickering headlight bulbs.

B. Using high beams when following another vehicle closely.

C. Driving so fast that your total stopping distance is longer than the distance you can see ahead. ✓ Correct Answer

Explanation: When you overdrive your headlights, you're traveling faster than you can stop within the area lit by your headlights. If an obstacle appears in the darkness ahead, you won't be able to stop in time to avoid a collision.

Q9: Why are engine retarders used on large commercial vehicles?

A. To help slow the vehicle down and reduce mechanical brake wear. ✓ Correct Answer

B. To provide extra horsepower during uphill mountain driving.

C. To prevent combination jackknifing on ice-covered roads.

Explanation: Engine retarders — such as exhaust brakes and Jake brakes — use engine resistance to help slow the vehicle, significantly reducing wear and heat on the service brakes. Important: turn off the engine retarder on wet, icy, or slippery roads to prevent wheel lockup and loss of control.

Q10: When dimming your high beams for an oncoming vehicle, federal law states you must switch to low beams within:

A. 500 feet. ✓ Correct Answer

B. 350 feet.

C. 250 feet.

Explanation: Dim your high beams within 500 feet of an oncoming vehicle. When following a vehicle ahead of you, switch to low beams within 350 feet. These two distances are both heavily tested on the CDL General Knowledge exam — don't mix them up.

CDL General Knowledge Test – Frequently Asked Questions

💡 How many questions are on the CDL General Knowledge test?

Many states use a 50-question CDL General Knowledge test, but the exact number of questions may vary depending on the state. Always check your state's official CDL manual for current testing details.

💡 What is the passing score for the CDL General Knowledge test?

Most states require a score of 80% or higher to pass the CDL General Knowledge test. However, testing requirements may vary by state, so applicants should verify the passing score with their state CDL handbook or licensing agency.

💡 Is the CDL General Knowledge test hard?

It can be tricky if you're new to commercial driving, since it tests very specific numbers, distances, and safety rules. But with consistent practice using this site's full question sets, most applicants pass on their first attempt.

💡 Can I take the CDL permit test in a language other than English?

Some states offer the CDL knowledge test in multiple languages — including California and New York. Many inland states, however, only offer it in English. Contact your local DMV to confirm what's available in your state.

💡 How many times can I retake the CDL knowledge test if I fail?

Rules vary by state. Most DMVs allow up to 3 attempts within a given period. After a failed test, you can typically reschedule as soon as the next business day after paying a small retest fee.