North Carolina Combination Vehicles CDL Practice Test

This is a free 20-question practice test for the Combination Vehicles portion of the North Carolina Commercial Driver's License knowledge exam. Questions are pulled from a pool of 55 drawn from the AAMVA CDL Manual, which is the source document the North Carolina Division of Motor Vehicles uses to write its actual exam.

How it works: Click an answer. The correct choice highlights in green, and you'll see a short explanation. Aim for 85% or better before you sit for the real test in North Carolina.

Question 1 of 20

Cargo securement: the heaviest part of the load should be:

Loaded over the front axle area, with weight evenly distributed side to side
Loaded at the rear
Loaded on one side
Stacked on top

Correct. Loading heavy cargo to the front of the trailer over the drive axles helps with traction; loading to one side or top creates dangerous handling.

Question 2 of 20

A jackknife happens when:

The trailer wheels skid while the tractor continues forward
The tractor pulls forward in a straight line
The trailer slides sideways while the tractor pivots
The driver brakes too lightly

Correct. Jackknife is when the drive wheels skid and the trailer continues forward, causing the tractor to pivot — the rig folds at the fifth wheel like a closing knife.

Question 3 of 20

When making a U-turn, a tractor-trailer needs:

Less space than a car
Substantially more space than a car — often more than a single intersection allows
The same space as a car
No turning space

Correct. Tractor-trailer turning radius is much larger than a car. A standard intersection rarely allows a U-turn — find a wider turning area.

Question 4 of 20

Trailer cargo can shift if:

Securement is inadequate, the load was packed unevenly, or the rig undergoes hard braking or sharp turns
Cargo never shifts
Roads are smooth
Trailer is empty

Correct. Inadequate securement, uneven packing, hard braking, sharp turns, or rough roads can all shift cargo. Inspect cargo periodically en route.

Question 5 of 20

When you are backing a trailer to the right, you should turn the steering wheel:

Left to start the trailer right
Right to start the trailer right
In the same direction every time
Never use the steering wheel; just push

Correct. When backing, the trailer goes opposite to the way you initially turn the steering wheel. To make the trailer go right (passenger side), start by turning the wheel left.

Question 6 of 20

When you connect the glad-hands, you should:

Cross-connect the red and blue lines so they cannot be confused
Connect both to the same color glad-hand
Pinch the seal first
Push them in straight without rotating

Correct. Push the glad-hands together so the rubber seals match, then rotate to lock. Be sure red goes to red and blue goes to blue (the lines themselves often cross to keep colors matched).

Question 7 of 20

Trailer rollover is more likely when:

Cargo is loaded low and centered
Cargo is loaded high or to one side, raising the center of gravity
Cargo is light
Trailer is empty

Correct. High cargo and uneven side-loading raise the center of gravity, increasing rollover risk on curves and ramps.

Question 8 of 20

When uncoupling, you should lower the landing gear:

After releasing the jaws
Before releasing the jaws so the trailer is supported when you pull away
Halfway
Not at all

Correct. Lower the landing gear and snug it against the ground before releasing the fifth-wheel jaws so the trailer doesn't drop when you pull away.

Question 9 of 20

A trailer that has been sitting may have:

Brakes that need careful adjustment, rust on the kingpin, or other issues that should be inspected
No issues — trailers are static
Built-in safety
Better brakes

Correct. Trailers idle for long periods can develop brake corrosion, kingpin rust, low tires, and other issues. Inspect carefully before use.

Question 10 of 20

When making a right turn at an intersection in a tractor-trailer:

Swing to the left first to make room for the right turn
Make the turn from the right lane and swing wide as needed at the end of the turn
Make the turn at high speed
Stay in the left lane through the turn

Correct. Make the turn from the right lane. If you must swing wide, do so as you complete the turn, never before — swinging left first invites a vehicle to pass on your right.

Question 11 of 20

When inspecting the kingpin during pre-trip, look for:

Excessive wear, bending, cracks, or improper lock-jaw engagement
Only the color
Only the size
Only the grease

Correct. A worn, cracked, or bent kingpin can fail under load. The locking jaws must close completely around the shank, not just the head.

Question 12 of 20

A sliding fifth wheel allows you to:

Adjust the weight distribution between drive axles and trailer axles
Speed up
Slow down
Disable the trailer brakes

Correct. Sliding fifth wheels move forward to put more weight on drive axles or aft to reduce drive-axle weight, helping comply with axle-weight limits.

Question 13 of 20

To make a trailer go where you want when backing, the steering wheel should:

Be turned in the direction you want the trailer to go
Be turned opposite to the direction you want the trailer to go (then corrected)
Stay still
Be held lightly

Correct. Backing is opposite-direction steering: to swing the trailer right, turn the wheel left first, then correct as the trailer follows.

Question 14 of 20

Length and weight increase what about a combination vehicle?

Stopping distance, off-tracking, blind spots, and time required for lane changes
Visibility
Speed
Acceleration

Correct. Longer, heavier rigs need more stopping distance, swing wider in turns, have larger blind spots, and require more time and space to change lanes.

Question 15 of 20

When you cross railroad tracks in a tractor-trailer, you should:

Shift gears to maintain speed
Cross in a single gear without shifting, and never start across without room to clear the rails
Stop on the tracks if the light turns red
Honk repeatedly

Correct. Crossing in one gear (without shifting) prevents stalling on the tracks. Never enter a crossing unless you can clear it without stopping.

Question 16 of 20

When you couple, the locking jaws of the fifth wheel must close around:

The kingpin shank, not just the head
Just the head
The trailer skirt
The wheel

Correct. The locking jaws must engage the kingpin shank below the head. If the jaws close above the head, the connection is unsafe.

Question 17 of 20

Before uncoupling, you should:

Park on level ground, set the trailer parking brake, lower the landing gear, disconnect air and electrical lines, then release the fifth-wheel jaws
Just pull away
Disconnect electrical only
Drive forward fast

Correct. Proper sequence: park level, lower landing gear to support the trailer, disconnect lines, release jaws, then pull forward slowly. Skipping any step risks dropping the trailer.

Question 18 of 20

When you turn on a tight radius (e.g., into a tight loading dock):

Off-tracking is exaggerated; the trailer will swing far inside the line of the tractor wheels
Off-tracking disappears
Trailer follows tractor exactly
Trailer goes wide

Correct. On a tight radius, off-tracking is more pronounced. Sweep wide enough that the trailer wheels clear curbs and obstacles.

Question 19 of 20

A sliding fifth wheel that is unlocked or improperly secured can:

Slide unexpectedly during braking or acceleration, dangerously changing handling
Improve fuel economy
Save time
Have no effect

Correct. An unsecured sliding fifth wheel can shift during braking, changing the rig's handling unpredictably. Always verify the lock pin is engaged.

Question 20 of 20

A "trailer skid" happens when:

Trailer wheels lose traction and the trailer slides outward
Tractor wheels lock
Brakes overheat
Cargo shifts

Correct. When trailer wheels lose traction (often from over-application of trailer brakes alone), the trailer can slide sideways — a trailer skid or trailer swing.

About the North Carolina Combination Vehicles exam

Most states administer 20 Combination Vehicles questions and require 80% to pass. The exam emphasizes the unique handling of articulated vehicles: how trailers track behind the tractor, how to prevent rollover, how to manage rearward amplification with multi-trailer combinations, and the correct sequence to couple and uncouple.

The North Carolina Division of Motor Vehicles follows the federal CDL standards established by FMCSA. To earn the Combination Vehicles credential, you must answer at least 80% of the questions correctly. Many candidates score lower the first time because the test pulls from a large pool — refreshing this page will give you a different mix of questions, drawn from the same authoritative source.

Want more practice? Try the full Combination Vehicles question bank or browse all North Carolina CDL practice tests.