CDL General Knowledge Practice Test 2026: Practice test 6

Practice test 6 of 6 for the CDL General Knowledge Practice Test: 25 more questions with answers and explanations.

Commercial vehicle
United States
150 questions
Checked October 10, 2026

Question 1 of 25
What does a round, black-on-yellow warning sign mean?
- A school is ahead
- A sharp curve is ahead
- Slow-moving vehicles are ahead
- A railroad crossing is ahead
Show answer
Answer: D. A railroad crossing is ahead
The round yellow advance sign warns that a railroad crossing is ahead: slow down, look and listen.
Question 2 of 25
Your low trailer gets stuck on a raised railroad crossing. What should you do first?
- Stay in the cab and honk
- Get out and away from the tracks, then call 911
- Try to rock the truck loose
- Walk down the track to look for a train
Show answer
Answer: B. Get out and away from the tracks, then call 911
Get out and move away from the tracks. Call 911 and give the crossing's location and DOT number if posted.
Question 3 of 25
To avoid a crash with an obstacle ahead, which is usually faster?
- Stopping
- Sounding the horn
- Steering around it
- Speeding up
Show answer
Answer: C. Steering around it
You can almost always turn to miss an obstacle more quickly than you can stop.
Question 4 of 25
When you steer quickly to avoid a crash, what should you avoid?
- Keeping both hands on the wheel
- Turning only as much as needed
- Countersteering once you pass the hazard
- Braking while you turn
Show answer
Answer: D. Braking while you turn
Do not brake while turning; it can lock the wheels and cause a skid.
Question 5 of 25
A driver coming toward you drifts into your lane. Which way should you move?
- To your right
- To your left
- Speed up
- Stay in your lane and brake hard
Show answer
Answer: A. To your right
When an oncoming driver drifts into your lane, a move to your right is best.
Question 6 of 25
What is controlled braking?
- Braking with the clutch pushed in
- Pumping the brakes as fast as possible
- Using only the parking brake to stop
- Braking hard without locking the wheels
Show answer
Answer: D. Braking hard without locking the wheels
In controlled braking you brake hard but not so hard that the wheels lock. Keep steering moves small.
Question 7 of 25
How do you do stab braking?
- Pump the brake pedal as fast as you can the whole time
- Pull the parking brake on and off again and again
- Brake lightly and hold the pedal down until you stop
- Brake fully, release when wheels lock, reapply when they roll
Show answer
Answer: D. Brake fully, release when wheels lock, reapply when they roll
In stab braking, apply the brakes fully, release when the wheels lock, and reapply as soon as they roll again.
Question 8 of 25
What does an antilock braking system (ABS) do?
- It always makes you stop in a shorter distance
- It stops wheel lockup so you can keep steering
- It replaces the normal brakes when they fail
- It lets you drive faster safely on slick roads
Show answer
Answer: B. It stops wheel lockup so you can keep steering
ABS keeps the wheels from locking so you can steer. It does not always shorten stopping distance.
Question 9 of 25
The ABS warning lamp stays on while you drive. What does this mean?
- ABS may not work, but normal brakes still do
- The parking brake has been left on
- Your air pressure is much too high
- You have no working brakes at all
Show answer
Answer: A. ABS may not work, but normal brakes still do
If ABS fails you still have regular brakes. Drive normally and have the system checked soon.
Question 10 of 25
Who is responsible for the cargo you haul if someone else loaded it?
- Only the shipper
- You, the driver
- No one, once the trailer is sealed
- Only the loader
Show answer
Answer: B. You, the driver
The driver is responsible for inspecting cargo and knowing it is safe, even if someone else loaded it.
Question 11 of 25
When must you first check your cargo and its securement after starting a trip?
- Within the first 50 miles
- Within the first 500 miles
- Only at the end of the trip
- Within the first 150 miles
Show answer
Answer: A. Within the first 50 miles
Check the cargo and securing devices within the first 50 miles and adjust them as needed.
Question 12 of 25
After the first check, how often must you re-check cargo securement?
- Once a day, at the start of each shift
- Every 3 hours or 150 miles, whichever comes first
- Only when a new driver takes over
- Every 500 miles, or at each fuel stop
Show answer
Answer: B. Every 3 hours or 150 miles, whichever comes first
Re-check cargo when your duty status changes, after 3 hours or 150 miles, whichever comes first.
Question 13 of 25
What is the gross vehicle weight rating (GVWR)?
- The weight carried by a single axle of the truck
- The weight of the empty truck with no fuel or cargo
- The weight limit posted by each city for its streets
- The maker's maximum weight for a vehicle and its load
Show answer
Answer: D. The maker's maximum weight for a vehicle and its load
GVWR is the manufacturer's maximum for the vehicle plus its load.
Question 14 of 25
What is gross combination weight (GCW)?
- The weight of the tractor alone, without its fuel
- The weight of the trailer only, without any cargo
- The weight of the cargo only, without any trailer
- The total weight of the power unit, trailers and cargo
Show answer
Answer: D. The total weight of the power unit, trailers and cargo
GCW is the total weight of the tractor or truck, its trailers, and the cargo.
Question 15 of 25
What does a bridge formula do?
- Sets the height limit for bridges
- Sets the speed limit on bridges
- Allows less weight on axles that are closer together
- Allows more weight on axles that are closer together
Show answer
Answer: C. Allows less weight on axles that are closer together
Bridge formulas limit the weight on axles that are close together to protect bridges and roads.
Question 16 of 25
How should you load cargo to avoid a high center of gravity?
- Low, with heavy items under light ones
- All the weight at the very back
- High, so it is easy to unload
- Heaviest items on top of the load
Show answer
Answer: A. Low, with heavy items under light ones
Keep the load low and put heavy items under lighter ones to lower the center of gravity.
Question 17 of 25
What can happen if there is too little weight on the drive axles?
- Better fuel use and a smoother ride
- Poor traction, so the drive wheels spin
- Overheated brakes on long downgrades
- Hard steering and a sore steering axle
Show answer
Answer: B. Poor traction, so the drive wheels spin
Too little weight on the drive axles gives poor traction, especially in bad weather.
Question 18 of 25
What is the minimum number of tiedowns for cargo on a flatbed?
- One per 10 feet of cargo, and at least two
- One for any load, no matter how long
- Four for any load, no matter how short
- One per 20 feet of cargo, at least one
Show answer
Answer: A. One per 10 feet of cargo, and at least two
Use at least one tiedown for each 10 feet of cargo. Any cargo, no matter how small, needs at least two.
Question 19 of 25
Under federal rules, how strong must a cargo securement system be?
- Its working load limit must be one-tenth of the cargo's weight
- Its working load limit must equal twice the truck's weight
- Any strap that fits is strong enough for any load
- Its working load limit must be at least half the cargo's weight
Show answer
Answer: D. Its working load limit must be at least half the cargo's weight
The aggregate working load limit of the securement system must be at least one-half the weight of the cargo.
Question 20 of 25
What does a header board (headache rack) do?
- Holds the license plate and lights
- Stops the trailer from swaying
- Protects you from cargo sliding forward
- Keeps rain from reaching the cargo
Show answer
Answer: C. Protects you from cargo sliding forward
The front-end structure protects the driver from the load moving forward.
Question 21 of 25
You are hauling a sealed load you cannot inspect. What must you still check?
- That gross and axle weight limits are not exceeded
- That the seal is the right color for the load
- Nothing; the shipper is responsible for all of it
- The value of the cargo, for insurance reasons
Show answer
Answer: A. That gross and axle weight limits are not exceeded
You cannot inspect sealed loads, but you must still make sure you are within weight limits.
Question 22 of 25
Why does hanging meat need special care?
- It is unstable and has a high center of gravity
- It must always ride on an open flatbed
- It must be kept below freezing by the driver
- It is too light to need any tiedowns at all
Show answer
Answer: A. It is unstable and has a high center of gravity
Hanging meat can swing and shift, making the vehicle less stable, especially on ramps and curves.
Question 23 of 25
When hauling less than a full load of livestock, what helps keep the animals from shifting?
- False bulkheads
- Driving faster
- Opening the side doors
- Tiedowns on each animal
Show answer
Answer: A. False bulkheads
False bulkheads keep livestock bunched together so they do not shift the center of gravity.
Question 24 of 25
What do oversized loads usually need?
- Nothing special if they are driven at night
- Special permits, and sometimes escort vehicles
- Only a Class C license and no permits
- Only an extra set of mirrors on the cab
Show answer
Answer: B. Special permits, and sometimes escort vehicles
Over-length, over-width or overweight loads need special permits and are often limited to certain times.
Question 25 of 25
Your load needs hazmat placards. What do you need on your CDL?
- No endorsement
- A passenger (P) endorsement
- A hazmat (H) endorsement
- A tank (N) endorsement
Show answer
Answer: C. A hazmat (H) endorsement
Any driver who hauls hazardous materials that need placards must have a hazmat endorsement.

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