TheoryCDL Class a
Practice Test
Pass the CDL Class A knowledge exam with 250+ questions covering general knowledge, air brakes, combination vehicles, and hazmat.
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CDL Class A exam — full Q&A walkthrough
Every question read aloud with the answer explained. Play it on your commute, then test yourself.
30 free CDL Class A questions
Sampled across every topic area — not just the first page. Try them as a quiz or flip them as flashcards.
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CDL Class A
During a pre-trip inspection, which component should you check for cracks, missing bolts, and proper mounting?
Correct — A. The CDL manual requires you to inspect the fifth wheel for cracks, broken or missing parts, and to verify it is properly mounted and locked before every trip. -
CDL Class A
What is the correct order to begin the 7-step pre-trip inspection?
Correct — C. Step 1 of the 7-step inspection is to approach and do an overview of the vehicle from a distance, looking for obvious damage, leaks, or tilting before moving closer. -
CDL Class A
During a pre-trip inspection of the engine compartment, which fluid level does the CDL manual specifically require you to check?
Correct — C. The CDL manual requires checking engine oil level as part of the engine compartment inspection; it must be at the proper level with no signs of leaks. -
CDL Class A
How many steps are in the standard CDL 7-step pre-trip inspection procedure?
Correct — B. The standard FMCSA/AAMVA CDL manual defines exactly 7 steps for the pre-trip vehicle inspection, covering everything from vehicle overview to signal and brake checks. -
CDL Class A
While driving, your low air pressure warning light and buzzer activate. According to the CDL manual, at approximately what air pressure does this warning typically trigger?
Correct — A. The CDL manual states the low air pressure warning device must activate before pressure drops below 60 psi, signaling the driver to stop safely and not continue driving. -
CDL Class A
During an en-route inspection stop, you notice one of your drive axle tires has a tread depth measuring 2/32 of an inch. What action is required?
Correct — C. Federal regulations require a minimum tread depth of 4/32 inch on front axle tires and all drive axle tires; 2/32 inch is only the minimum for other positions, so a drive axle at 2/32 is an out-of-service condition. -
CDL Class A
Which of the following brake defects found during inspection would place a vehicle out of service?
Correct — C. A cracked brake drum is a critical out-of-service defect per FMCSA regulations because it compromises braking performance and could lead to complete brake failure. -
CDL Class A
During a pre-trip inspection of the coupling, you push forward on the trailer and the fifth wheel does not release. What does this indicate?
Correct — C. Pushing forward on the trailer while the tractor is in low gear and not releasing confirms the fifth wheel is properly locked onto the kingpin, which is a required part of the coupling inspection. -
CDL Class A
During your pre-trip walk-around, you find that one running light on the trailer is not working. What must you do before driving?
Correct — B. Any lighting defect that affects required safety equipment must be repaired before the vehicle is operated; noting defects does not satisfy the requirement if the equipment is needed for legal operation. -
CDL Class A
During a pre-trip inspection of a vehicle with air brakes, you fan the brakes to reduce air pressure. At approximately what pressure should the spring (parking) brakes automatically activate?
Correct — C. The CDL manual states that spring brakes should automatically activate (pop out) when air pressure falls into the range of approximately 20 to 45 psi, with the generally tested threshold around 40 psi, ensuring the vehicle is held if air is lost. -
CDL Class A
When starting a loaded tractor-trailer on a level surface, which gear should you typically begin in?
Correct — B. The CDL manual instructs drivers to start in a low gear appropriate for the load and road conditions so the vehicle moves smoothly without excessive clutch wear or slippage. -
CDL Class A
When coming to a stop in a vehicle equipped with a manual transmission, what is the correct procedure for the clutch?
Correct — B. The CDL manual states you should keep the clutch engaged while braking to use engine braking, and only disengage the clutch when the engine speed drops too low, just before the vehicle stops. -
CDL Class A
When backing a straight truck, your first action after checking mirrors should be to:
Correct — D. The CDL manual's 'GOAL' principle (Get Out And Look) requires the driver to physically inspect the path behind the vehicle before any backing maneuver to identify obstacles and hazards. -
CDL Class A
Which of the following best describes the purpose of a retarder on a large commercial vehicle?
Correct — A. The CDL manual explains that retarders (engine, exhaust, hydraulic, or electric) help slow the vehicle without using the service brakes, reducing brake wear and heat on long downgrades. -
CDL Class A
During the double-clutching technique, what happens between the first and second clutch disengagement?
Correct — A. Double-clutching requires pushing the clutch in and moving to neutral, then releasing the clutch and adjusting RPM to match road speed, then pushing the clutch in again and selecting the target gear so gear speeds are synchronized. -
CDL Class A
When should a driver turn OFF a vehicle's retarder?
Correct — B. The CDL manual warns that retarders can cause the rear wheels to skid on slippery surfaces because they apply braking force only to the drive axles; drivers should turn them off in slippery conditions. -
CDL Class A
If you miss a gear while shifting upward through a multi-speed transmission, what is the correct response?
Correct — C. The CDL manual advises that if a gear cannot be engaged cleanly, the driver should return to neutral, re-match RPM to road speed, and reattempt the shift rather than forcing the lever. -
CDL Class A
What does road speed (vehicle speed in mph) have to do with when you shift gears?
Correct — A. The CDL manual notes that drivers can use road speed as a guide for shifting because each gear corresponds to a road speed range, which is particularly useful when a tachometer is absent or difficult to read. -
CDL Class A
A driver is backing a 53-foot trailer into a dock using a 90-degree blind-side backing maneuver. After the initial setup, the driver realizes the trailer is drifting wide. What is the correct steering correction?
Correct — B. When backing, steering away from the drift (toward the side the trailer is drifting toward) causes the rear of the trailer to swing back toward the intended path; this is the standard CDL manual correction technique for off-track backing. -
CDL Class A
A driver is descending a 6% grade in a fully loaded combination vehicle. After several miles, the driver notices the service brakes feel 'spongy' and require more pedal travel than normal. The MOST likely cause is:
Correct — A. The CDL manual identifies brake fade as a condition caused by overheating of the brakes from prolonged or excessive application on downgrades; proper technique is to use a low gear and apply brakes in short firm applications rather than riding them continuously. -
CDL Class A
When double-clutching an upshift in a 10-speed transmission under a heavy load at highway speed, the driver releases the accelerator and moves to neutral. Before completing the shift into the next higher gear, engine RPM should be:
Correct — C. During an upshift, the driver must allow RPM to drop in neutral so that the engine speed matches the slower input-shaft speed required by the higher gear at the current road speed; engaging with too-high RPM causes a harsh clunk and driveline shock. -
CDL Class A
How far ahead should a commercial driver look when driving at highway speeds?
Correct — D. The CDL manual instructs drivers to look 12 to 15 seconds ahead at highway speeds to identify hazards early enough to respond safely. -
CDL Class A
When driving in city traffic at lower speeds, how far ahead should a commercial driver scan?
Correct — B. At city speeds the CDL manual recommends scanning at least one city block ahead, which equates to roughly 12 seconds of travel time and provides adequate hazard recognition distance. -
CDL Class A
When is it appropriate to use your horn while operating a commercial motor vehicle?
Correct — C. The CDL manual identifies the horn as a safety device to be used when needed to warn others and help prevent a collision, not as a routine courtesy signal. -
CDL Class A
Which side of a tractor-trailer has the largest blind spot?
Correct — A. The CDL manual identifies the right-side blind spot as the largest danger zone because it extends diagonally from the cab past the entire length of the trailer, making vehicles alongside the right side invisible to the driver. -
CDL Class A
When preparing to change lanes on a multi-lane highway, after signaling a driver should do what before moving?
Correct — D. The CDL manual emphasizes that a turn signal communicates intent; the driver must verify the move is safe and give other drivers adequate time to respond before executing the lane change. -
CDL Class A
You are stopped at a red light that turns green. What should you do before moving the vehicle?
Correct — C. The CDL manual instructs drivers to re-check mirrors and scan the intersection before proceeding on a green light because other vehicles may have run the red or pedestrians may be in the crosswalk. -
CDL Class A
What is the CDL manual's baseline following-distance rule for a vehicle over 40 feet long traveling at speeds above 40 mph?
Correct — A. The CDL manual requires one second per 10 feet of vehicle length as the base following distance, with one additional second added whenever speed exceeds 40 mph. -
CDL Class A
When backing a tractor-trailer, which mirrors are most useful for monitoring the path directly behind the trailer on both sides?
Correct — C. The CDL manual directs drivers to use both flat primary mirrors while backing so they can track the trailer's movement and verify clearance along each side. -
CDL Class A
A driver is operating a 70-foot combination vehicle at 55 mph. Using the CDL manual's following-distance formula, what is the correct minimum following distance?
Correct — D. The CDL manual requires one second per 10 feet of vehicle length (70 feet = 7 seconds) plus one additional second for speeds above 40 mph, giving a minimum of 8 seconds total.
CDL Class A sample questions
Tap any question below to reveal the answer and a plain-English explanation.
CDL Class A When driving in city traffic at lower speeds, how far ahead should a commercial driver scan?
A. About 1 to 2 seconds ahead
B. One full city block ahead ✓
C. Just past the front bumper of the vehicle
D. 30 to 40 seconds ahead
Correct — B. At city speeds the CDL manual recommends scanning at least one city block ahead, which equates to roughly 12 seconds of travel time and provides adequate hazard recognition distance.
CDL Class A When is it appropriate to use your horn while operating a commercial motor vehicle?
A. Routinely before every intersection to alert pedestrians
B. Only to express frustration at slow traffic
C. To warn others of your presence when necessary to help avoid a collision ✓
D. Whenever you are merging onto a highway
Correct — C. The CDL manual identifies the horn as a safety device to be used when needed to warn others and help prevent a collision, not as a routine courtesy signal.
CDL Class A Which side of a tractor-trailer has the largest blind spot?
A. The passenger's right side, extending diagonally toward the rear of the trailer ✓
B. Directly behind the trailer
C. Directly in front of the cab
D. On the driver's left side
Correct — A. The CDL manual identifies the right-side blind spot as the largest danger zone because it extends diagonally from the cab past the entire length of the trailer, making vehicles alongside the right side invisible to the driver.
CDL Class A When preparing to change lanes on a multi-lane highway, after signaling a driver should do what before moving?
A. Move immediately as long as a mirror was checked
B. Wait exactly 3 seconds then move
C. Flash the signal twice more then proceed
D. Confirm it is safe and allow surrounding drivers enough time to react to the signal ✓
Correct — D. The CDL manual emphasizes that a turn signal communicates intent; the driver must verify the move is safe and give other drivers adequate time to respond before executing the lane change.
CDL Class A You are stopped at a red light that turns green. What should you do before moving the vehicle?
A. Sound the horn once and proceed immediately
B. Shift directly into the highest gear to clear the intersection quickly
C. Check all mirrors and scan the intersection for any crossing traffic or pedestrians ✓
D. Flash your headlights to alert cross traffic
Correct — C. The CDL manual instructs drivers to re-check mirrors and scan the intersection before proceeding on a green light because other vehicles may have run the red or pedestrians may be in the crosswalk.
CDL Class A What is the CDL manual's baseline following-distance rule for a vehicle over 40 feet long traveling at speeds above 40 mph?
A. One second of following distance for every 10 feet of vehicle length, plus one additional second ✓
B. One second for every 5 feet of vehicle length
C. Four seconds regardless of vehicle length or speed
D. Two car lengths at all speeds
Correct — A. The CDL manual requires one second per 10 feet of vehicle length as the base following distance, with one additional second added whenever speed exceeds 40 mph.
CDL Class A When backing a tractor-trailer, which mirrors are most useful for monitoring the path directly behind the trailer on both sides?
A. The convex wide-angle mirrors mounted on the front bumper
B. The in-cab backup camera display alone
C. The flat primary (plane) mirrors on both sides of the cab ✓
D. An overhead interior rearview mirror
Correct — C. The CDL manual directs drivers to use both flat primary mirrors while backing so they can track the trailer's movement and verify clearance along each side.
CDL Class A A driver is operating a 70-foot combination vehicle at 55 mph. Using the CDL manual's following-distance formula, what is the correct minimum following distance?
A. 6 seconds
B. 7 seconds
C. 9 seconds
D. 8 seconds ✓
Correct — D. The CDL manual requires one second per 10 feet of vehicle length (70 feet = 7 seconds) plus one additional second for speeds above 40 mph, giving a minimum of 8 seconds total.
About the CDL Class A test
Study smarter for the US Commercial Driver's License (CDL) Class A knowledge exam. This app gives you original practice questions built from the publicly available AAMVA model CDL manual and FMCSA rules that every state follows, with a clear explanation for every answer.
What you get
- General Knowledge: vehicle inspection, basic control and shifting, space and speed management, hazardous conditions, emergencies, cargo, alcohol and fatigue rules.
- Air Brakes: system parts, dual air systems, inspecting and using air brakes.
- Combination Vehicles: coupling and uncoupling, inspection, rollover and trailer safety.
- Three difficulty levels and a clear explanation citing the rule for every question.
- Timed practice tests that mirror real exam length and pass mark.
Original & safe
Every question is written for this app from the public CDL manual and federal rules. Nothing is copied from any real state exam, test pool or third-party question bank.
You will be tested on
- Road signs, signals and markings
- Right-of-way and intersection rules
- Speed, stopping distances and safe following
- Hazard perception and defensive driving
How TheoryPractice helps you pass
- Real exam-style questions with instant, detailed explanations
- Full timed mock exams that mirror the real test format
- Flashcards & quiz modes from the same question bank
- Progress tracking so you know exactly when you're ready
Topics in this question bank
Road signs, signals and markings
Right-of-way and intersection rules
Speed, stopping distances and safe following
Hazard perception and defensive driving
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