California General Knowledge CDL Practice Test
25 realistic General Knowledge practice questions for California CDL applicants. Required for: All CDL applicants (Class A, B, and C). Official test: 50 questions, 40 correct to pass.
Question 1 of 25 · Driver Wellness
Which of the following is NOT a sign of fatigued driving?
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A.
Frequent yawning
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B.
Drifting from your lane
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C.
Rapid blinking and clear focus
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D.
Missing exits or traffic signs
Correct answer: C.
Rapid blinking with clear focus is not a fatigue sign. Yawning, drifting, and missing exits all are.
Question 2 of 25 · Following Distance
Following distance for a heavy vehicle traveling below 40 mph should be at least:
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A.
1 second per 10 feet of vehicle length
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B.
Half the length of the vehicle
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C.
Two seconds total
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D.
No specific amount required
Correct answer: A.
Use one second of following distance for every 10 feet of vehicle length below 40 mph; add a second above 40 mph.
Question 3 of 25 · Driver Wellness
Aggressive drivers should be:
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A.
Confronted
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B.
Reported and given plenty of room
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C.
Followed closely
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D.
Passed quickly without signaling
Correct answer: B.
Stay clear of aggressive drivers and report dangerous behavior to authorities.
Question 4 of 25 · Driver Wellness
Which of these statements about staying alert to drive is true?
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A.
Coffee will overcome fatigue
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B.
You can rely on caffeine to stay awake
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C.
There is no substitute for sleep
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D.
Cold air will keep you alert all night
Correct answer: C.
There is no substitute for adequate rest. Caffeine and cold air provide only temporary alertness.
Question 5 of 25 · Cargo
How can you tell if your vehicle is overloaded?
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A.
It rides higher than normal
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B.
It handles differently from when properly loaded
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C.
It uses less fuel
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D.
It accelerates faster
Correct answer: B.
Overloaded vehicles handle poorly — they accelerate slower, take longer to stop, and are harder to steer.
Question 6 of 25 · Night Driving
You should use low beam headlights:
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A.
Whenever you can
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B.
Within 500 feet of an oncoming vehicle and 500 feet behind another vehicle
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C.
Only in fog
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D.
On lighted city streets only
Correct answer: B.
Use low beams within 500 feet of oncoming traffic and when following within 500 feet of another vehicle.
Question 7 of 25 · Inspection
Vehicle inspection is important because:
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A.
Federal and state laws require it
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B.
Safety is at risk
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C.
Defects can save lives if found early
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D.
All of the above
Correct answer: D.
Inspections are legally required and prevent breakdowns and crashes by catching defects early.
Question 8 of 25 · Backing
The most important hand signal you and a helper should agree on is:
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A.
Speed up
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B.
Stop
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C.
Turn left
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D.
Back straight
Correct answer: B.
Always agree on a clear stop signal before backing. The helper must be able to stop you instantly.
Question 9 of 25 · Speed Management
Engine brakes (Jakes) should not be used:
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A.
On dry pavement at highway speed
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B.
On slippery roads while loaded or empty
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C.
When descending a steep grade
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D.
Heading toward a long downhill
Correct answer: B.
Avoid engine brakes on slippery roads — they can cause the drive wheels to lose traction.
Question 10 of 25 · Emergency Equipment
When stopped on the side of a level, straight, two-lane road, where should the three reflective triangles be placed?
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A.
10, 50, and 100 feet behind the vehicle
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B.
10, 100, and 200 feet behind the vehicle
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C.
On the front, side, and rear of the vehicle
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D.
50, 100, and 200 feet on the traffic side
Correct answer: B.
Triangles go 10, 100, and 200 feet behind the vehicle on a straight, level, two-lane road.
Question 11 of 25 · Cargo
Which is correct about cargo and weight balance?
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A.
Heavy cargo should always be at the rear
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B.
Cargo should be balanced and secured to prevent shifting
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C.
Side-to-side balance does not matter
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D.
Top-heavy loads improve stability
Correct answer: B.
Cargo must be evenly balanced and well secured. Top-heavy loads increase rollover risk.
Question 12 of 25 · Speed Management
When you double your speed, your stopping distance is multiplied by approximately:
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A.
Two
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B.
Three
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C.
Four
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D.
Six
Correct answer: C.
Stopping distance grows with the square of speed. Doubling speed roughly quadruples the distance needed to stop.
Question 13 of 25 · Vehicle Dynamics
Empty trucks:
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A.
Always stop more quickly than loaded trucks
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B.
Have less traction because there is less weight on the drive axles
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C.
Can take curves at higher speeds safely
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D.
Are not affected by wind
Correct answer: B.
Empty trucks have reduced traction on drive axles and require greater stopping distances than loaded trucks.
Question 14 of 25 · Rail Crossings
When approaching a railroad crossing without flashing lights or gates, you should:
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A.
Slow down, look, and listen for trains
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B.
Always come to a complete stop
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C.
Speed up to clear the crossing quickly
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D.
Sound horn but maintain speed
Correct answer: A.
Without active warning devices, slow down and look and listen carefully for an approaching train.
Question 15 of 25 · Inspection
The proper way to test the service brake on a vehicle is to:
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A.
Pump the pedal three times
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B.
Push the brake pedal firmly while moving about 5 mph
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C.
Put the parking brake on
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D.
Listen for air leaks
Correct answer: B.
Move the vehicle forward at about 5 mph and apply the brake firmly. The vehicle should not pull to either side.
Question 16 of 25 · Inspection
What is the minimum tread depth for non-steering axle tires?
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A.
1/32 inch
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B.
2/32 inch
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C.
4/32 inch
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D.
6/32 inch
Correct answer: B.
Federal regulations require at least 2/32 inch on non-steering tires.
Question 17 of 25 · Adverse Conditions
Hydroplaning is most likely to occur when:
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A.
Tires are properly inflated
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B.
Speed is below 30 mph
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C.
Roads are dry
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D.
Tires lose contact with the road on wet pavement
Correct answer: D.
Hydroplaning happens when water builds up between the tire and the road, causing loss of contact.
Question 18 of 25 · Adverse Conditions
Which of the following is true about driving in fog?
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A.
You should always drive with high beams
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B.
Avoid driving in fog if possible
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C.
Use the right edge of the road as a guide rather than the center line
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D.
Both b and c
Correct answer: D.
Avoid driving in fog when possible. If unavoidable, use low beams and the right edge as a guide.
Question 19 of 25 · Inspection
Pre-trip inspection of the vehicle should be done in the same order each time so that you:
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A.
Will look professional to other drivers
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B.
Will learn it well and not skip anything
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C.
Can finish faster
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D.
Pass the test more easily
Correct answer: B.
Following the same order helps prevent missed steps and builds reliable habits.
Question 20 of 25 · Driver Wellness
Distracted driving includes:
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A.
Talking on a hand-held cell phone
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B.
Eating
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C.
Reading maps
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D.
All of the above
Correct answer: D.
All of these activities take attention from driving and are forms of distracted driving.
Question 21 of 25 · Driver Wellness
You should not eat or drink while driving because:
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A.
It is illegal in all states
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B.
Spills can distract you
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C.
You should not put both hands on the wheel
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D.
It might damage the vehicle
Correct answer: B.
Eating and drinking divert attention and create spill hazards.
Question 22 of 25 · Inspection
Excessive heat in tires can:
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A.
Improve handling
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B.
Cause tire failure
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C.
Help fuel economy
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D.
Increase tire life
Correct answer: B.
Excessive heat causes blowouts and serious damage. Check for hot tires after driving.
Question 23 of 25 · Adverse Conditions
When you have to drive into the sun and visibility is reduced, what should you do?
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A.
Use sunglasses and lower the visor
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B.
Use only your high beams
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C.
Maintain your normal speed
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D.
Speed up to get past the area
Correct answer: A.
Use sunglasses and the visor and slow down. Reduced visibility increases stopping distance.
Question 24 of 25 · Speed Management
You are driving a vehicle that could safely be driven at 55 mph on an open highway. The traffic is heavy and moving at 35 mph. The safest speed for your vehicle in this traffic is most likely:
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A.
25 mph
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B.
35 mph
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C.
45 mph
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D.
55 mph
Correct answer: B.
You should generally adjust to the speed of surrounding traffic when it is safe to do so.
Question 25 of 25 · Backing
Which of these statements about backing a heavy vehicle is true?
-
A.
Back in a curved path whenever possible
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B.
Avoid backing whenever you can
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C.
Back as quickly as possible
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D.
Use only the right mirror
Correct answer: B.
Avoid backing whenever you can. Park where you will be able to pull forward to leave.
About the General Knowledge Test
The General Knowledge test covers safe vehicle inspection, basic vehicle control, shifting gears, communicating, controlling speed, controlling distance, seeing hazards, distracted driving, aggressive drivers, communicating with other drivers, night driving, driving in fog, winter driving, hot weather driving, mountain driving, driving emergencies, anti-lock braking systems, skid recovery, accident procedures, fires, alcohol and other drugs, hazardous materials awareness, and staying alert and fit to drive. Every commercial driver in the United States must pass this test before any other CDL endorsement can be added.
The California Department of Motor Vehicles administers this knowledge test as part of its commercial driver license program. To earn the CDL General Knowledge on your California CDL, you need to score at least 40 out of 50 on the official version.
Topics covered on this practice test
- Driver Wellness: 5 questions
- Inspection: 5 questions
- Speed Management: 3 questions
- Adverse Conditions: 3 questions
- Cargo: 2 questions
- Backing: 2 questions
- Following Distance: 1 question
- Night Driving: 1 question
- Emergency Equipment: 1 question
- Vehicle Dynamics: 1 question
- Rail Crossings: 1 question
How to use this practice test
- Read each question carefully. CDL questions are written precisely — small wording differences matter.
- Click "Show Answers & Explanations" only after answering every question. Don't peek mid-test.
- Read the explanation for every question, even ones you got right. The reasoning is more important than the answer.
- Repeat the test until you score 100%. The questions are deterministic per state, so you can track your improvement over multiple sessions.
- Move on to the other endorsement tests for California until you're ready for the official exam.
Tips specific to the General Knowledge test
The General Knowledge test is the foundation of every CDL. Topics include vehicle inspection, basic control, shifting, communicating, controlling speed, controlling space, hazard perception, distracted driving, night driving, fog, winter, hot weather, mountain driving, emergencies, anti-lock brakes, skid recovery, accident procedures, fires, alcohol, hazardous materials awareness, and staying alert. Most failures come from speeding through inspection-related questions; slow down and read carefully.
Other practice tests for California