Free CDL General Knowledge Practice Test 2026
The foundation for commercial driving: inspections, space, speed, communication, hazards, and safe operation. Knowledge tests are federal: you need 80% on each one (49 CFR 383.135(a)(1)), whether you test in Texas, California, or anywhere else. QuizLane has 231 reviewed general knowledge questions with explanations.
- Pre-trip inspection
- Space and speed management
- Railroad crossings
- Emergency procedures
Sample questions
5 general knowledge practice questions
Each sample shows the correct answer with a plain-language explanation. The full 231-question bank is in the practice run after you pick a state.
1. While operating a commercial motor vehicle, the driver must:
- Wear a safety belt
- BWear a safety belt only on interstates
- CUse the belt only under 40 mph
- DRely on the air bag alone
Answer: Wear a safety belt. Federal rules require the driver to wear a seat belt when the vehicle is equipped with one.
2. Driving much faster than surrounding traffic generally:
- AReduces crash risk
- Increases passing and fatigue, raising crash risk
- CIs required on interstates
- DImproves fuel economy always
Answer: Increases passing and fatigue, raising crash risk. Constantly passing is tiring and multiplies conflict points. Going with the flow is safer when conditions allow.
3. Why should a driver avoid shifting gears while crossing railroad tracks?
- AIt increases tire pressure
- BIt turns off warning lights
- CIt can make mirrors vibrate
- A missed shift could leave the vehicle stalled on the tracks
Answer: A missed shift could leave the vehicle stalled on the tracks. Select the proper gear before entering the crossing and do not change gears until the vehicle is completely across.
4. No matter how short a piece of cargo is, it should have at least:
- AFour tiedowns
- BNo tiedowns if under 50 pounds
- COne tiedown
- Two tiedowns
Answer: Two tiedowns. Also use at least one tiedown for every 10 feet of cargo length as a general rule.
5. DOT requires ABS on truck tractors with air brakes built on or after:
- AMarch 1, 2005
- BMarch 1, 1995
- March 1, 1997
- DMarch 1, 2000
Answer: March 1, 1997. Other air-brake vehicles (trucks, buses, trailers, dollies) generally need ABS if built on or after March 1, 1998; heavier hydraulic trucks/buses from March 1, 1999.
Common questions
Before you start this CDL practice test
Other CDL knowledge tests
Keep going topic by topic.
- Air brakes
- Combination vehicles
- Hazardous materials
- Tank vehicles
- Doubles & triples
- Passenger vehicles
- School bus
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