U.S. CDL · QUESTIONS & ANSWERS

U.S. CDL General Knowledge Practice — questions and answers

All 36 original Rig Toolbox practice questions for this test, printed in full with the correct answer and an explanation for each one. Read them here, then put them to work in Practice or the Exam Simulator — no sign-up, ever.

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Independent practice: these are Rig Toolbox's own study questions, not official exam questions. Always confirm rules in the official handbook for the licence you are taking.

About this question set

How many questions are here? 36 — the full bank for this test. The interactive test draws 20 of them at a time.

What is this test? Original general-knowledge practice. State manuals and testing details vary.

Every question, with its answer

Question 1

Before backing a commercial vehicle, first:

Back quickly
Get out and inspect the path
Use one mirror
Sound the horn and move

Correct answer: Get out and inspect the path

Get out and look so hazards and clearance are known.

Question 2

Why is a pre-trip inspection important?

It replaces maintenance
It helps find safety problems before driving
It is only for new trucks
It removes reporting

Correct answer: It helps find safety problems before driving

A systematic inspection helps identify defects.

Question 3

When should cargo securement be checked?

Only at delivery
Before travel and as required during the trip
Only by the shipper
After unloading

Correct answer: Before travel and as required during the trip

Cargo must remain properly secured throughout the trip.

Question 4

Before descending a steep grade:

Shift to neutral
Select a safe speed and proper gear
Turn off the engine
Accelerate

Correct answer: Select a safe speed and proper gear

Choose the safe speed and gear before the descent.

Question 5

What is off-tracking?

Rear wheels follow a shorter path in a turn
A GPS failure
Speeding
A brake adjustment

Correct answer: Rear wheels follow a shorter path in a turn

Rear wheels track inside the steering-wheel path.

Question 6

If overhead clearance is uncertain:

Continue slowly
Stop safely and verify
Follow another truck
Use the shoulder

Correct answer: Stop safely and verify

Never guess about clearance.

Question 7

If a tire fails:

Brake hard
Hold the wheel firmly and slow gradually
Turn sharply
Accelerate

Correct answer: Hold the wheel firmly and slow gradually

Maintain control and avoid sudden braking.

Question 8

Why inspect coupling equipment?

Improve fuel mileage
Prevent tractor-trailer separation
Reduce paperwork
Change cargo weight

Correct answer: Prevent tractor-trailer separation

The fifth wheel, kingpin and lock must be engaged.

Question 9

At night, drive at a speed that lets you:

Stop within the visible distance
Outrun traffic
Use parking lights only
Ignore following distance

Correct answer: Stop within the visible distance

Stopping distance must fit the visible road.

Question 10

A blind spot is:

An area not visible directly or in mirrors
A dark road
Windshield damage
A closed scale

Correct answer: An area not visible directly or in mirrors

Commercial vehicles have areas the driver cannot see.

Question 11

What helps prevent rollover on a curve?

Enter faster
Slow before the curve
Brake hard halfway through
Change lanes

Correct answer: Slow before the curve

Reduce speed before the curve and steer smoothly.

Question 12

Where should applicants confirm CDL test rules?

Social media
The state licensing agency issuing the CDL
A fuel station
A dealer

Correct answer: The state licensing agency issuing the CDL

States administer CDL tests under federal standards.

Question 13

Which document is the best source for your state CDL knowledge test?

A different state manual
The CDL manual from the issuing state
A social media checklist
A vehicle advertisement

Correct answer: The CDL manual from the issuing state

States publish their own CDL manuals under federal testing standards.

Question 14

Why should a driver check mirrors regularly during a trip?

To replace a walk-around
To stay aware of traffic around the vehicle
To avoid using signals
To estimate fuel price

Correct answer: To stay aware of traffic around the vehicle

Mirror checks help maintain awareness of changing traffic.

Question 15

If the trailer begins tracking closer to the inside of a turn, what is this called?

Off-tracking
Hydroplaning
Engine braking
Oversteer

Correct answer: Off-tracking

A long trailer follows a tighter path than the front wheels.

Question 16

What is an important reason to leave extra following space in a large vehicle?

It shortens the vehicle
It gives time and room to respond
It guarantees green lights
It replaces a speed limit

Correct answer: It gives time and room to respond

Space gives more time to perceive, react and stop.

Question 17

When visibility falls in heavy rain, which action helps?

Increase speed
Reduce speed and increase space
Turn off all lights
Follow tail lamps closely

Correct answer: Reduce speed and increase space

Lower speed and more space help when visibility and traction are reduced.

Question 18

What should you do if a mirror is loose before departure?

Ignore it if the other mirror works
Report and correct the visibility problem before travel
Tape over it
Drive only in the right lane

Correct answer: Report and correct the visibility problem before travel

Adequate mirrors are necessary for visibility around the vehicle.

Question 19

Why should the route be checked for low clearances?

Only to save fuel
A vehicle may not fit beneath a structure
To avoid map apps
Only for empty trailers

Correct answer: A vehicle may not fit beneath a structure

A planned route must account for the actual vehicle height.

Question 20

What should a driver do before a lane change?

Signal and move immediately
Check mirrors, blind spots and space before moving
Rely on another driver to brake
Change lanes while braking sharply

Correct answer: Check mirrors, blind spots and space before moving

Verify the destination lane is clear before moving.

Question 21

A tire looks underinflated during inspection. What is the prudent response?

Ignore it until next week
Check and address it according to procedures before travel
Increase speed to warm it
Remove the valve cap

Correct answer: Check and address it according to procedures before travel

A suspect tire condition needs proper evaluation and correction.

Question 22

What does the term gross combination weight describe?

Only the tractor
Combined weight of powered unit, trailer and cargo
Only freight
Only the trailer

Correct answer: Combined weight of powered unit, trailer and cargo

Gross combination weight includes the combination and its load.

Question 23

Why should cargo be secured before a trip?

To make unloading faster
To prevent shifting or falling during travel
To replace the bill of lading
Only for international trips

Correct answer: To prevent shifting or falling during travel

Securement protects road users and helps keep the load stable.

Question 24

When approaching a curve in a loaded vehicle, when should speed be adjusted?

Before entering the curve
Halfway through the curve
Only after the turn
Never

Correct answer: Before entering the curve

Choose a suitable speed before the curve.

Question 25

What is a safe response when unsure whether there is enough room to back?

Keep moving and hope
Stop, get out and check clearance
Only watch one mirror
Ask traffic to move

Correct answer: Stop, get out and check clearance

Verify the path and clearance before continuing.

Question 26

Why is a post-trip vehicle report useful?

It substitutes for repair
It communicates defects to the carrier or next driver
It changes license class
It sets a speed limit

Correct answer: It communicates defects to the carrier or next driver

Reporting helps defects get addressed before the vehicle is used again.

Question 27

A commercial vehicle has a longer stopping distance. What does this mean for speed?

Higher speed makes no difference
Plan ahead and leave more stopping room
Follow traffic more closely
Only brake near an intersection

Correct answer: Plan ahead and leave more stopping room

Stopping distance grows with speed, so planning and space matter.

Question 28

What should you verify after coupling a trailer?

Only that the marker lights look bright
The coupling is secure and connections are properly made
Only the truck color
That landing gear remains down

Correct answer: The coupling is secure and connections are properly made

A walk-around confirms the connection and trailer readiness.

Question 29

When merging, what should you do if there is no safe gap?

Force entry
Wait for a safe opportunity
Stop in a live travel lane
Assume others will move

Correct answer: Wait for a safe opportunity

Do not merge until there is adequate space.

Question 30

What is a common sign of a load that may have shifted?

A new fuel receipt
A change in handling or visible movement
A clean windshield
A working radio

Correct answer: A change in handling or visible movement

A changed load position can alter handling and requires a safe inspection.

Question 31

Why inspect lights and reflectors before leaving?

They are decorative
They help other road users see the vehicle and its signals
They reduce tire wear
They replace mirrors

Correct answer: They help other road users see the vehicle and its signals

Visible lights and reflectors support communication and conspicuity.

Question 32

How should drivers confirm a current federal hours-of-service rule?

Use a random quiz answer
Check the current FMCSA guidance and applicable regulations
Ask another driver only
Assume all trips use identical exceptions

Correct answer: Check the current FMCSA guidance and applicable regulations

FMCSA guidance and rules provide the applicable details and exceptions.

Question 33

What should a driver do if a roadside inspection finds a defect requiring repair?

Continue without reporting
Follow the inspector and carrier instructions before operating
Hide the report
Leave the scene without paperwork

Correct answer: Follow the inspector and carrier instructions before operating

Inspection findings must be handled as directed by the applicable rules.

Question 34

Why might a vehicle need more room while turning?

The trailer can off-track into a smaller inside arc
The tractor shrinks during a turn
The turn signal changes size
The mirrors extend the trailer

Correct answer: The trailer can off-track into a smaller inside arc

Long combinations have a path difference between front and rear wheels.

Question 35

What is the purpose of checking the air and electrical connections?

Only appearance
To make sure the connected equipment functions and lines are secure
To speed up fueling
To determine cargo value

Correct answer: To make sure the connected equipment functions and lines are secure

Connections must be secure and free of damage for proper operation.

Question 36

When the roadway is icy, which choice reduces risk?

Hard braking
Slow, smooth control and more space
Using cruise control
Close following

Correct answer: Slow, smooth control and more space

Reduced traction calls for slower, smoother actions and more space.

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