CDL General Knowledge Practice Test — 40 Free Questions (Unofficial)
An unofficial practice set for the CDL general knowledge test. 40 original multiple-choice questions on driver readiness, hours of service, inspection and tires, cargo securement, rail crossings and emergency equipment, each with a short explanation.
- Questions: 40 multiple choice, each with an explanation.
- Based on: Federal Motor Carrier Safety Regulations, 49 CFR Parts 383, 392, 393, 395 and 396 (public-domain U.S. government text, read on eCFR).
- Affiliation: Unofficial. Not affiliated with any exam board, agency or state.
- Last reviewed: 2026-11-04.
Topics covered
- Driver Readiness and Distraction
- Inspection and Tire Safety
- Emergency Equipment and Cab Hazards
- Cargo Inspection and Securement
- Safe Operation and Rail Crossings
- Hours of Service Basics
All 40 questions with answers
Try each question first, then open the answer. To practice them as a timed quiz with a score and a mistake list, use the practice test.
Driver Readiness and Distraction
1. A property-carrying CMV driver is so fatigued that safe operation is impaired. There is no grave emergency. What should happen?
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Answer: C. Do not begin or continue driving in that unsafe condition
Being within an hours limit does not authorize driving while unsafe from fatigue.
2. A CMV driver plans to go on duty at noon. Under the federal operating rule, which preceding period is subject to the alcohol-use prohibition?
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Answer: D. The four hours before going on duty
Section 392.5 prohibits alcohol use within four hours before going on duty or operating; on-duty prohibitions also apply.
3. A driver is on duty with a CMV and says a small drink is acceptable because there will be no driving for an hour. What does the federal rule require?
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Answer: C. No alcohol use while on duty
The on-duty prohibition is separate from a driver's estimate of when driving will resume.
Inspection and Tire Safety
4. A driver finds that a required windshield wiper will not operate before a trip. What is the proper decision under the equipment rule?
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Answer: B. Do not drive until satisfied the required equipment is in good working order
Required listed equipment must be in good working order before the CMV is driven.
5. Before driving, what must a CMV driver be satisfied about the vehicle?
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Answer: D. It is in safe operating condition
The inspection requirement concerns safe operating condition, not cosmetic or vendor uniformity.
6. A last driver vehicle inspection report is required for the vehicle. What must the next driver do before driving?
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Answer: C. Review that required report
Section 396.13 requires review of the last report where that report is required; not every operation has identical reporting duties.
7. At a major tread groove, what is the minimum federal tread depth for a truck's front-wheel tire, excluding tie bars and similar features?
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Answer: A. 4/32 inch
The front-wheel minimum in section 393.75(b) is 4/32 inch.
8. For a CMV tire not covered by the front-wheel rule, what is the minimum major-groove tread depth under section 393.75(c)?
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Answer: A. 2/32 inch
The general minimum outside the front-wheel provision is 2/32 inch.
9. A tire's sidewall has a cut exposing body-ply material. What does the federal tire rule require?
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Answer: C. Do not operate the vehicle on that tire
Exposed ply or belt material is a prohibited tire condition independent of tread depth.
10. A CMV tire has an audible air leak. Which action meets the federal operating restriction?
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Answer: C. Keep the vehicle out of operation on that tire until corrected
A flat tire or one with an audible leak is prohibited for operation.
Emergency Equipment and Cab Hazards
11. For a power unit not transporting hazardous materials, which extinguisher arrangement satisfies the listed minimum rating choice?
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Answer: A. One extinguisher rated at least 5 B:C
The alternative is two extinguishers rated at least 4 B:C each; this option uses the one-extinguisher minimum.
12. A power unit carries hazardous materials in a quantity requiring placards. What minimum extinguisher rating applies?
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Answer: A. 10 B:C
The placarded-hazardous-material operation has a minimum 10 B:C rating.
13. A required extinguisher is loose under cargo and cannot be reached readily. Which change is required?
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Answer: A. Securely mount it where it is readily accessible
Required extinguishers must be accessible and securely mounted to prevent movement.
14. Which option meets the reflective-triangle choice for stopped-vehicle warning equipment?
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Answer: C. Three compliant bidirectional emergency reflective triangles
Three compliant bidirectional reflective triangles are one allowed warning-device option; other allowed options have their own conditions.
Cargo Inspection and Securement
15. A truck's accessible cargo can be inspected, and no sealed-load exception applies. By what point must the initial en-route cargo and securement inspection occur?
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Answer: C. Within the first 50 miles
The first en-route inspection must occur within fifty miles, in addition to the pre-trip assurance.
16. After the initial cargo inspection, a truck reaches three hours of driving before covering 150 miles. No exception applies. What is required?
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Answer: D. Reexamine the cargo and securement now
Reexamination is triggered by three hours, 150 miles, or a duty-status change, whichever occurs first.
17. A truck reaches 150 miles since cargo reexamination after only two hours. No exception applies. What should the driver do?
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Answer: D. Reexamine cargo and securement at that trigger
The distance trigger applies even when the time trigger has not yet occurred.
18. A truck driver changes duty status before three driving hours or 150 miles have elapsed since cargo reexamination. No exception applies. Which statement is correct?
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Answer: C. The duty-status change is itself a reexamination trigger
The listed triggers are alternatives, not cumulative conditions.
19. A sealed vehicle's driver has been ordered not to open it for cargo inspection. Which statement reflects the specific exception?
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Answer: C. The en-route inspection rules in paragraph (b) have an exception for that case
The exception is limited to paragraph (b); it is not a blanket exemption from safe operation.
20. A load shifts enough to impair a truck's stability even though nothing falls off. Is containment against falling alone sufficient?
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Answer: C. No; securement must also prevent shifting that harms stability or maneuverability
The cargo standard addresses harmful shifting as well as loss of cargo from the vehicle.
21. Loose material is blowing off a vehicle onto a public road. Which cargo-control objective is not being met?
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Answer: A. Preventing cargo from leaking, spilling, blowing, or falling from the vehicle
Public-road cargo transport must prevent the listed forms of cargo loss.
22. A package in the cab blocks the driver's clear view to the right and obstructs access to emergency equipment. What is required before operation?
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Answer: B. Reposition and secure it so it no longer creates those obstructions
Cargo must not impair the required view, movement, emergency access, or exit.
Safe Operation and Rail Crossings
23. A local rule is less protective than an applicable FMCSA operating requirement. Which standard must be met?
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Answer: D. The higher standard of care imposed by the FMCSA requirement
Section 392.2 requires compliance with the FMCSA provision when it imposes a higher standard of care.
24. A dispatch schedule could be met only by exceeding posted speed limits. What should the carrier do?
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Answer: A. Use a schedule that does not require unlawful speeds
A carrier may not schedule or require operation that necessitates exceeding jurisdictional speed limits.
25. An ordinary CMV is not among vehicles required to make the special stop under section 392.10. What is required on approach to a railroad crossing?
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Answer: B. Approach at a speed allowing a stop before the nearest rail and ensure the way is clear
The absence of the special mandatory-stop category does not remove the duty to slow and exercise caution.
26. Traffic beyond a railway crossing is backed up, leaving too little room for the entire CMV beyond the tracks. What should the driver do?
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Answer: B. Wait before entering until there is space to clear completely without stopping
The CMV must not enter without enough space to pass fully through without stopping.
27. Rain reduces traction on the route. The posted speed limit has not changed. What does the federal rule require?
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Answer: D. Reduce speed and exercise extreme caution
Hazardous visibility or traction conditions require caution and reduced speed.
28. Fog becomes so severe that a freight CMV cannot be operated safely. No passenger emergency applies. What should happen?
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Answer: D. Discontinue operation until safe operation is possible
When conditions become sufficiently dangerous, operation must stop until it can safely resume.
Driver Readiness and Distraction
29. A property-carrying CMV has an installed driver seat-belt assembly. What is required for operation?
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Answer: D. The driver must be properly restrained by it
The federal seat-belt requirement applies to the driver in this specified equipped property-carrying vehicle.
30. While temporarily stopped at a red light during a CMV trip with the engine running, a driver wants to type a non-emergency text. What does the texting rule say?
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Answer: C. The temporary traffic stop is still included in driving for this rule
The texting prohibition includes temporary stops caused by traffic or traffic-control devices.
31. A CMV driver wants to hold a phone in one hand to make a routine voice call while driving. What is the rule?
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Answer: A. Hand-held mobile-telephone use is prohibited
The restriction addresses hand-held telephone use, with a limited emergency-communication exception.
32. A driver needs to contact emergency services because of an immediate emergency. Which statement reflects the stated telephone-rule exception?
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Answer: C. Use necessary to communicate with law enforcement or emergency services is permitted
The exception is specific to communication with law enforcement or emergency services, not routine dispatch calls.
Hours of Service Basics
33. A property-carrying driver subject to the general interstate HOS rules has taken ten consecutive hours off duty, and no exception applies. What is the normal maximum driving time afterward?
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Answer: A. 11 hours
The general property-carrying driving maximum is eleven hours after ten consecutive hours off duty, subject to other limits.
34. Under the general interstate property-carrying rules, what happens after the fourteenth consecutive hour following coming on duty, with no exception or qualifying sleeper split?
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Answer: C. The driver may not drive, even if fewer than eleven driving hours were used
The fourteen-hour driving window and eleven-hour driving limit are separate restrictions.
35. A property-carrying driver covered by the general break rule has accumulated eight driving hours without a thirty-minute interruption. What is required before more driving?
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Answer: B. A qualifying thirty-consecutive-minute non-driving interruption
The break can be on-duty not driving, off duty, sleeper berth, or a qualifying consecutive combination; applicable exceptions must be considered.
36. Which period can satisfy the general property-carrying thirty-minute driving-break requirement if the other conditions apply?
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Answer: D. Thirty consecutive minutes on duty but not driving
The qualifying interruption need not be entirely off duty, but it must be non-driving and thirty consecutive minutes.
37. A property-carrying driver wants to restart the general seven/eight-day HOS period. What off-duty duration can qualify under the standard restart provision?
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Answer: A. At least 34 consecutive hours
The standard property-carrying restart can follow thirty-four or more consecutive hours off duty.
Emergency Equipment and Cab Hazards
38. A closed CMV body will carry a person. What must be available inside that body?
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Answer: D. An exit mechanism the occupant can readily operate
The occupant must have an operable means of exit from inside.
39. Carbon monoxide is detected inside a CMV. What must happen before it is dispatched or driven again?
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Answer: C. The condition must be remedied or repaired
The rule bars dispatch or driving when the listed carbon-monoxide conditions are known until corrected.
40. A driver places a radar detector in the cab but says it will remain unused. What does the federal CMV rule prohibit?
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Answer: A. Operation of a CMV containing a radar detector, not just its active use
Section 392.71 prohibits driving a CMV equipped with or containing a radar detector.
Frequently asked questions
Is this an official exam?
No. These are original, unofficial practice questions written by PocketLearn. They are not released exam items. Your state CDL manual and the state knowledge test are the final word; this set covers federal rules, not state-specific items.
How many questions are there?
40 multiple-choice questions in 6 topics. Each question has an explanation.
Is it free?
Yes. You can open the practice set without an account; signing in lets you save progress and review mistakes.
Can I use it on my phone?
It opens in a mobile browser. A laptop or tablet is easier for longer sets.