Most people think they’re ready for the CDL permit test… until they run into questions like these. These 10 questions are missed all the time by new drivers — and a few surprise experienced truckers too.
Try them yourself. If you miss more than 3, it’s a clear sign you need a bit more practice before you walk into the real exam.
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Why These “Gotcha” Questions Matter
Below you’ll see 10 CDL-style questions with three answer choices each. Try to answer them honestly before looking at the answer and explanation.
These are based on the topics you’ll see in the CDL General Knowledge, Combination Vehicles, Air Brakes, and basic safety sections of the official CDL manuals.
10 CDL Questions Almost Everyone Misses
You’re driving a 70-foot combination vehicle at 55 mph on a clear, dry highway. How many seconds of following distance should you keep?
- A. 4 seconds
- B. 7 seconds
- C. 8 seconds
Correct Answer: C
CDL manuals teach the “1 second for every 10 feet of vehicle” rule for speeds below 40 mph. Over 40 mph, you add 1 extra second. A 70-foot combination needs 7 seconds + 1 extra = 8 seconds of following distance.
When should you downshift and use engine braking on a long downhill grade?
- A. Only when your service brakes start to fade
- B. Before you start down the hill
- C. After you’re halfway down the hill
Correct Answer: B
You should downshift before you start down a steep hill. Do not try to shift while going downhill — you can lose control if you miss the gear and the vehicle freewheels.
Your trailer starts to jackknife while you’re braking. What should you do first?
- A. Accelerate to straighten out the trailer
- B. Apply more trailer brake
- C. Release the brakes
Correct Answer: C
Jackknifing usually means the wheels have locked up. Locked wheels slide sideways and the trailer starts to swing. The first step is to release the brakes so the wheels can roll again and the trailer can straighten out.
What does ABS (anti-lock braking system) help prevent?
- A. Skids from locked wheels
- B. Rollovers in sharp curves
- C. Brake fade on long downgrades
Correct Answer: A
ABS keeps your wheels from locking up during hard braking. It doesn’t help you stop shorter on dry pavement, but it helps you keep steering control and avoid skids.
When should you test the parking brake on a combination vehicle?
- A. Only during the pre-trip inspection
- B. Every time you park for more than 10 minutes
- C. When the vehicle is moving slowly, around 5 mph
Correct Answer: C
The CDL pre-trip includes a parking brake test where you gently apply the parking brake while moving slowly, usually about 5 mph, to make sure the brake holds and the vehicle slows down properly.
Which fire extinguisher rating is appropriate for most commercial motor vehicles?
- A. A only
- B. ABC
- C. BC only
Correct Answer: B
Many CDL manuals require a 5-B:C extinguisher at minimum, but an ABC rated extinguisher works on trash/wood (A), liquids (B), and electrical fires (C). It’s the most flexible choice.
You notice thick black smoke coming from your exhaust. What does this usually mean?
- A. Engine overheating
- B. Unburned fuel / too much fuel
- C. Low coolant level
Correct Answer: B
Black smoke usually means too much fuel is being burned or not burning completely — often caused by a dirty air filter, injector problems, or poor air–fuel mix.
Where are the main “no-zones” (blind spots) around a tractor-trailer?
- A. Only directly behind the trailer
- B. On all four sides of the truck
- C. Only on the passenger side
Correct Answer: B
Large commercial vehicles have big blind spots: in front, behind, and along both sides. These areas are often called “no-zones” because cars should avoid staying in them.
If your brakes get wet while driving in heavy rain or after going through deep water, what should you do?
- A. Pump them hard until they dry
- B. Accelerate to blow-dry them faster
- C. Drive slowly and gently apply the brakes
Correct Answer: C
Wet brakes can grab or pull to one side. The safe method is to drive slowly and lightly apply the brakes so they dry out without locking or pulling.
When backing a trailer, how should you turn the top of the steering wheel to control the direction of the trailer?
- A. Turn the top of the wheel toward the direction you want the trailer to go
- B. Turn the top of the wheel opposite the trailer’s direction
- C. It doesn’t matter; only the tractor direction changes
Correct Answer: A
A simple way to remember backing is: turn the top of the steering wheel toward the direction you want the trailer to go. This makes it easier to control the trailer when backing into a spot.
How Did You Score?
Be honest with yourself:
- 10 / 10: You’re looking solid for the CDL permit test.
- 7 – 9 correct: Almost ready — review your weak spots.
- 4 – 6 correct: Keep studying before you schedule your exam.
- 0 – 3 correct: Do not rush your test date yet.
Share this quiz with a friend who’s getting their CDL and compare scores. Drivers love testing each other with questions like these.
Ready for Real CDL Practice Tests?
These 10 questions are just a warm-up. On FreeCDLTests.com you can take full-length, free CDL practice tests based on the official 2025 CDL manual — with instant feedback and simple explanations.