South Dakota General Knowledge CDL Practice Test
25 realistic General Knowledge practice questions for South Dakota CDL applicants. Required for: All CDL applicants (Class A, B, and C). Official test: 50 questions, 40 correct to pass.
Question 1 of 25 · Hazard Awareness
When approaching a vehicle with a flashing amber light, you should:
-
A.
Speed up to pass it
-
B.
Slow down and pass with caution
-
C.
Stop and wait until the light is off
-
D.
Honk and continue
Correct answer: B.
Amber flashing lights indicate a hazard or slow-moving vehicle. Slow down and pass carefully.
Question 2 of 25 · CDL Rules
Driving with a BAC of 0.04 or higher in a CMV will result in:
-
A.
A warning
-
B.
A 30-day suspension
-
C.
A CDL disqualification of at least one year
-
D.
No penalty if off-duty
Correct answer: C.
A first offense disqualifies you for at least one year (three years if hauling hazardous materials).
Question 3 of 25 · Inspection
Excessive heat in tires can:
-
A.
Improve handling
-
B.
Cause tire failure
-
C.
Help fuel economy
-
D.
Increase tire life
Correct answer: B.
Excessive heat causes blowouts and serious damage. Check for hot tires after driving.
Question 4 of 25 · Inspection
What is the most important reason for doing a vehicle inspection?
-
A.
To meet DOT requirements
-
B.
Safety for yourself and others
-
C.
To save fuel
-
D.
To avoid roadside inspections
Correct answer: B.
Safety is the most important reason. A defective vehicle puts you, your cargo, and others at risk.
Question 5 of 25 · Driver Wellness
Aggressive drivers should be:
-
A.
Confronted
-
B.
Reported and given plenty of room
-
C.
Followed closely
-
D.
Passed quickly without signaling
Correct answer: B.
Stay clear of aggressive drivers and report dangerous behavior to authorities.
Question 6 of 25 · Following Distance
Following distance for a heavy vehicle traveling below 40 mph should be at least:
-
A.
1 second per 10 feet of vehicle length
-
B.
Half the length of the vehicle
-
C.
Two seconds total
-
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 7 of 25 · ABS
ABS:
-
A.
Allows you to drive faster
-
B.
Lets you brake hard without losing steering control
-
C.
Means you don't have to use safe driving techniques
-
D.
Eliminates the need to inspect brakes
Correct answer: B.
ABS preserves steering during emergency braking but does not shorten stopping distance.
Question 8 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:
-
A.
25 mph
-
B.
35 mph
-
C.
45 mph
-
D.
55 mph
Correct answer: B.
You should generally adjust to the speed of surrounding traffic when it is safe to do so.
Question 9 of 25 · Inspection
When checking the engine compartment, your vehicle should be:
-
A.
Idling in neutral
-
B.
On a slight incline
-
C.
Parked on level ground with the parking brake set and wheels chocked
-
D.
Running with the parking brake off
Correct answer: C.
Always inspect the engine compartment with the vehicle parked on level ground, parking brake set, and wheels chocked.
Question 10 of 25 · Emergency Maneuvers
Controlled braking is:
-
A.
Pressing the brake to the floor and holding
-
B.
Applying brakes hard enough to lock the wheels
-
C.
Applying brakes to keep wheels just short of locking
-
D.
Releasing brakes and coasting
Correct answer: C.
Controlled braking applies the brake firmly without locking the wheels, keeping the steering straight.
Question 11 of 25 · Hazard Awareness
How can you tell if your truck or bus has a hazardous materials shipment?
-
A.
It is moving slowly
-
B.
Diamond-shaped placards are displayed
-
C.
A flashing yellow light is on
-
D.
It is following another truck
Correct answer: B.
Diamond-shaped placards on the vehicle indicate the presence of hazardous materials.
Question 12 of 25 · Mountain Driving
When driving down a long, steep downgrade, you should:
-
A.
Apply the brakes lightly to keep the speed down
-
B.
Use a low gear and engine braking with intermittent braking
-
C.
Coast in neutral
-
D.
Press brakes continuously
Correct answer: B.
Use the appropriate low gear, rely on engine braking, and apply service brakes intermittently to control speed.
Question 13 of 25 · Adverse Conditions
Hydroplaning is most likely to occur when:
-
A.
Tires are properly inflated
-
B.
Speed is below 30 mph
-
C.
Roads are dry
-
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 14 of 25 · Adverse Conditions
What should you do before driving in fog?
-
A.
Use high beams to see further
-
B.
Slow down and use low beams and fog lights if equipped
-
C.
Speed up to clear the fog area
-
D.
Follow another vehicle closely
Correct answer: B.
Slow down before entering fog. Use low beams and any installed fog lights.
Question 15 of 25 · Emergency Maneuvers
What should you do if your brakes fail on a downgrade?
-
A.
Pump the brakes vigorously
-
B.
Look for an escape ramp or open area to slow down
-
C.
Shift into neutral
-
D.
Turn off the engine
Correct answer: B.
If brakes fail, look for an escape ramp or a route that will slow your vehicle without endangering others.
Question 16 of 25 · Emergency Maneuvers
Which of the following is a sign of tire failure?
-
A.
A loud "bang" sound
-
B.
Vibration or thumping
-
C.
Heavy steering or fishtailing
-
D.
All of the above
Correct answer: D.
A bang, vibration, heavy steering, or fishtailing can all indicate tire failure.
Question 17 of 25 · Inspection
Pre-trip inspection of the vehicle should be done in the same order each time so that you:
-
A.
Will look professional to other drivers
-
B.
Will learn it well and not skip anything
-
C.
Can finish faster
-
D.
Pass the test more easily
Correct answer: B.
Following the same order helps prevent missed steps and builds reliable habits.
Question 18 of 25 · Speed Management
When you double your speed, your stopping distance is multiplied by approximately:
-
A.
Two
-
B.
Three
-
C.
Four
-
D.
Six
Correct answer: C.
Stopping distance grows with the square of speed. Doubling speed roughly quadruples the distance needed to stop.
Question 19 of 25 · Speed Management
Engine retarders should be turned off when:
-
A.
Driving uphill
-
B.
The road is wet, icy, or snow covered
-
C.
Traffic is heavy
-
D.
You are loaded
Correct answer: B.
Retarders can cause drive wheels to skid on slippery surfaces. Turn them off in poor traction conditions.
Question 20 of 25 · Vehicle Dynamics
Empty trucks:
-
A.
Always stop more quickly than loaded trucks
-
B.
Have less traction because there is less weight on the drive axles
-
C.
Can take curves at higher speeds safely
-
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 21 of 25 · Adverse Conditions
Black ice is:
-
A.
A thick layer of ice that is easily seen
-
B.
A thin layer that looks wet pavement
-
C.
Only found in the far north
-
D.
Not a real road hazard
Correct answer: B.
Black ice is a thin, transparent layer that looks like wet pavement. It is extremely dangerous.
Question 22 of 25 · ABS
What does ABS do?
-
A.
Helps you stop faster
-
B.
Prevents wheels from locking up during hard braking
-
C.
Replaces engine brakes
-
D.
Eliminates the need for service brakes
Correct answer: B.
Antilock braking systems prevent wheel lockup, helping you maintain steering control during hard braking.
Question 23 of 25 · Speed Management
Engine brakes (Jakes) should not be used:
-
A.
On dry pavement at highway speed
-
B.
On slippery roads while loaded or empty
-
C.
When descending a steep grade
-
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 24 of 25 · Emergency Equipment
What three kinds of emergency equipment must you have in your vehicle?
-
A.
Spare tire, fuses, and reflective triangles
-
B.
Fire extinguisher, spare fuses (if equipped), and warning devices
-
C.
First aid kit, water, and flares
-
D.
Tool kit, fuel can, and flag
Correct answer: B.
You must have a fire extinguisher, spare electrical fuses (if equipped), and warning devices for stopped vehicles.
Question 25 of 25 · Basic Control
Which of these is the proper way to hold a steering wheel?
-
A.
One hand at 12 o'clock
-
B.
Both hands on opposite sides of the wheel
-
C.
Both hands on top
-
D.
One hand at 6 o'clock
Correct answer: B.
Hold the wheel firmly with both hands placed on opposite sides for full control.
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 South Dakota Driver Licensing Program administers this knowledge test as part of its commercial driver license program. To earn the CDL General Knowledge on your South Dakota CDL, you need to score at least 40 out of 50 on the official version.
Topics covered on this practice test
- Inspection: 4 questions
- Speed Management: 4 questions
- Emergency Maneuvers: 3 questions
- Adverse Conditions: 3 questions
- Hazard Awareness: 2 questions
- ABS: 2 questions
- CDL Rules: 1 question
- Driver Wellness: 1 question
- Following Distance: 1 question
- Mountain Driving: 1 question
- Vehicle Dynamics: 1 question
- Emergency Equipment: 1 question
- Basic Control: 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 South Dakota 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 South Dakota