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CDL general knowledge practice test 8

25 more questions on general knowledge, written from the Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual.

25 questions

  1. Question 1When you test the service brakes, the vehicle pulls to one side. What can this mean?

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    A: There may be brake trouble. Pulling to one side, an unusual pedal feel or delayed stopping can all mean brake trouble. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.1.5 Seven-step inspection method, page 41.

  2. Question 2What is by far the most common type of skid?

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    C: A drive-wheel (rear-wheel) skid. The most common skid by far happens when the rear (drive) wheels lose grip from braking or accelerating too hard. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.19.1 Drive-wheel skids, page 90.

  3. Question 3During which hours do many heavy motor vehicle crashes occur?

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    A: Between midnight and 6 a.m.. The hours from midnight to 6 a.m. account for many heavy-vehicle crashes. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.11.2 Driver factors, page 72.

  4. Question 4How many placards must a placarded vehicle have, and where?

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    B: At least four identical placards: front, rear and both sides. A placarded vehicle must have at least four identical placards on the front, rear and both sides, readable from all four directions. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.23.3 Lists of regulated products, page 96.

  5. Question 5How do you test the parking brake on a power unit?

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    D: Set it, put the vehicle in a low gear and gently pull forward against it. With the parking brake set, place the vehicle in a low gear and gently pull forward to make sure it holds. If it doesn't, it is faulty. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.1.5 Seven-step inspection method, page 41.

  6. Question 6How do you stop a drive-wheel skid caused by acceleration on ice or snow?

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    B: Take your foot off the accelerator (and push the clutch in if it is very slippery). Acceleration skids can be stopped by taking your foot off the accelerator; if very slippery, push in the clutch so the wheels can roll freely. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.19.1 Drive-wheel skids, page 90.

  7. Question 7How much sleep do adults need to stay alert, according to the manual?

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    C: 8 to 9 hours. Adults need 8 to 9 hours of sleep to maintain alertness. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.11.2 Driver factors, page 73.

  8. Question 8What is the minimum size of a hazardous materials placard?

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    B: About 9.8 inches (250 mm) square. Placards must be at least 9.8 inches (250 mm) square, turned upright on a point in a diamond shape. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.23.3 Lists of regulated products, page 96.

  9. Question 9Why should you secure all loose articles in the cab before driving?

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    C: They may interfere with the controls or hit you in a crash. Loose items can interfere with operating the controls or hit you in a crash. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.1.5 Seven-step inspection method, page 41.

  10. Question 10In a vehicle towing a trailer, what can a drive-wheel skid cause?

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    A: The trailer pushes the towing vehicle sideways, causing a sudden jackknife. When the drive wheels skid on a rig towing a trailer, the trailer can shove the tractor sideways and jackknife suddenly. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.19.1 Drive-wheel skids, page 90.

  11. Question 11On long trips, about how often should you take breaks?

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    B: Every 100 miles or 2 hours. On a long trip, stop for a break roughly every 2 hours or 100 miles. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.11.2 Driver factors, page 73.

  12. Question 12Hazardous materials identification numbers on shipping papers are preceded by which letters?

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    D: "UN" or "NA". The four-digit identification number is preceded by "NA" or "UN"; the Emergency Response Guidebook lists the chemicals and their numbers. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.23.3 Lists of regulated products, page 97.

  13. Question 13Drivers transporting cargo must inspect the cargo securement within the first how many miles of a trip?

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    B: 50 miles. Cargo securement must be inspected within the first 50 miles of a trip. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.1.6 Inspection during a trip, page 42.

  14. Question 14What is the correct order of actions to correct a drive-wheel braking skid?

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    A: Stop braking, steer quickly where you want to go, then countersteer. Stop braking so the rear wheels roll again, quickly steer in the direction you want to go, then countersteer as the vehicle comes back on course. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.19.2 Correcting a drive-wheel braking skid, page 90.

  15. Question 15If you are drowsy while driving, what is the only safe cure?

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    A: Get off the road and get some sleep. Caffeine wears off and drugs won't make you alert; the only safe cure is to get off the road and sleep. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.11.2 Driver factors, page 73.

  16. Question 16Who uses the four-digit hazardous materials identification numbers to identify the materials?

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    C: First responders. First responders use the four-digit identification number to tell which hazardous material is involved. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.23.3 Lists of regulated products, page 97.

  17. Question 17After the first cargo check, how often must truck drivers re-check cargo securement?

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    A: Every 150 miles or every 3 hours, whichever comes first. After the first check, re-inspect every 150 miles or every 3 hours, whichever comes first. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.1.6 Inspection during a trip, page 42.

  18. Question 18What is the only way to stop a front-wheel skid?

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    C: Let the vehicle slow down: stop turning and/or braking so hard. In a front-wheel skid the front end goes straight no matter how you steer; the only way to stop it is to let the vehicle slow down. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.19.3 Front-wheel skids, page 91.

  19. Question 19About how far ahead can you see with low-beam headlights?

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    B: 250 feet. With low beams you can see ahead about 250 feet; with high beams about 350–500 feet. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.11.4 Vehicle factors, page 74.

  20. Question 20Your vehicle carries hazardous materials but does not require placards. Do you need the HazMat endorsement to drive it?

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    A: No, the endorsement is required when the vehicle needs placards. You can drive a vehicle carrying hazardous materials if it doesn't require placards; if it does require placards, you need the HazMat endorsement. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.23.3 Lists of regulated products, page 97.

  21. Question 21How long should you keep a copy of your after-trip vehicle inspection report in the vehicle?

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    D: One day. Keep a copy of the report in the vehicle for one day so the next driver can learn about any problems found. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.1.7 After-trip inspection and report, page 42.

  22. Question 22Besides driving too fast, what can cause a front-wheel skid?

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    B: Lack of tread on the front tires or too little weight on the front axle. Most front-wheel skids come from driving too fast; other causes are lack of front tire tread and cargo loaded with too little weight on the front axle. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.19.3 Front-wheel skids, page 91.

  23. Question 23How much light may dirty headlights give?

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    C: Only about half the light they should. Dirty headlights may give only half the light they should, which cuts your vision and makes you harder to see. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.11.4 Vehicle factors, page 74.

  24. Question 24Does a tank endorsement apply only to hazardous liquids?

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    A: No, the liquid or gas does not have to be a hazardous material. The tank endorsement applies to tanks meeting the capacity thresholds, and the liquid or gas does not have to be hazardous. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.23.3 Lists of regulated products, page 97.

  25. Question 25In a vehicle with a manual transmission, how do you keep from rolling back when you start?

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    C: Partly engage the clutch before taking your right foot off the brake. With a manual transmission, start to engage the clutch before lifting your right foot from the brake, and use the parking brake if needed to hold the vehicle. Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual: 2.2.1 Accelerating, page 43.

Answer every question to see your score.

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Our own questions, written from the Wisconsin Commercial Driver's Manual (BDS356), based on the AAMVA 2025 CDL Manual (May 2026), official manual, and checked against it.