CDL General Knowledge Practice Test 2026: Practice test 5

Practice test 5 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 are escape ramps for?
- Parking overnight
- Checking brakes on flat ground
- Letting slow trucks pass
- Stopping runaway vehicles safely
Show answer
Answer: D. Stopping runaway vehicles safely
Escape ramps are built to stop vehicles whose brakes have failed. Know where they are on your route.
Question 2 of 25
What is the following distance rule for heavy vehicles?
- 1 second per 10 feet of length, plus 1 second over 40 mph
- 1 second per 20 feet of length at any speed
- 2 seconds for any vehicle at any speed
- 1 car length for each 10 mph of speed
Show answer
Answer: A. 1 second per 10 feet of length, plus 1 second over 40 mph
Leave 1 second for every 10 feet of length below 40 mph, and add 1 second above 40 mph.
Question 3 of 25
Your truck is 40 feet long and you are driving at 35 mph. What following distance should you keep?
- At least 2 seconds
- At least 4 seconds
- At least 8 seconds
- At least 5 seconds
Show answer
Answer: B. At least 4 seconds
40 feet means 4 seconds. Because you are below 40 mph, you do not add the extra second.
Question 4 of 25
Your rig is 60 feet long and you are driving at 55 mph. What following distance should you keep?
- At least 4 seconds
- At least 7 seconds
- At least 3 seconds
- At least 6 seconds
Show answer
Answer: B. At least 7 seconds
60 feet means 6 seconds, plus 1 more second because you are above 40 mph.
Question 5 of 25
Someone is tailgating you. What should you do?
- Leave more space ahead and avoid quick changes
- Speed up to get away from them
- Slow down suddenly to make them back off
- Flash your brake lights to warn them
Show answer
Answer: A. Leave more space ahead and avoid quick changes
Give yourself more space ahead so you will not have to stop suddenly. Do not speed up or play tricks with your lights.
Question 6 of 25
Which vehicle is more likely to hit a low bridge or overhang?
- An empty van
- They are always the same height
- A loaded van
- A loaded flatbed with a low load
Show answer
Answer: A. An empty van
An empty van rides higher than a loaded one. Also, do not assume posted heights are correct.
Question 7 of 25
The diagram shows a tractor-trailer making a tight right turn. What is the right way to make the turn?
- Turn sharply from the left lane
- Let the trailer roll over the curb
- Keep the rear by the curb; swing wide as you finish
- Swing wide to the left before you start the turn
Show answer
Answer: C. Keep the rear by the curb; swing wide as you finish
Turn slowly, keep the rear close to the curb, and use the lane you are entering as you complete the turn.
Question 8 of 25
Why should you not swing left before making a right turn in a large vehicle?
- A car may try to pass you on the right
- It wears out your steering tires quickly
- It is always illegal in every state
- It makes the trailer jackknife in the turn
Show answer
Answer: A. A car may try to pass you on the right
If you swing left first, a car may slip in on your right. Swing wide as you complete the turn instead.
Question 9 of 25
When turning left in a large vehicle, when should you start the turn?
- At the center of the intersection
- From the right-hand lane
- Before you reach the intersection
- As soon as you see a gap
Show answer
Answer: A. At the center of the intersection
Go to the center of the intersection before you turn left, so your rear wheels do not cut the corner.
Question 10 of 25
There are two left-turn lanes. Which one should a large vehicle use?
- Neither; go straight instead
- Either one
- The left-hand turn lane
- The right-hand turn lane
Show answer
Answer: D. The right-hand turn lane
Use the right-hand lane of two left-turn lanes. You may need to swing right to clear the turn.
Question 11 of 25
Distraction makes you react half a second slower. What does this do to crash risk?
- It doubles it
- It has no real effect
- It lowers it
- It raises it a little
Show answer
Answer: A. It doubles it
Reacting just half a second slower because of a distraction doubles the chance of a crash.
Question 12 of 25
What is the safest way to make or take a phone call?
- Pull off the road safely first
- Text instead of calling
- Hold the phone low and keep driving
- Call only on straight roads
Show answer
Answer: A. Pull off the road safely first
Pull over to a safe spot before using your phone. Even hands-free calls distract you.
Question 13 of 25
An aggressive driver confronts you. What should you do?
- Speed up to stay ahead of them
- Get out of the way; avoid eye contact
- Brake suddenly in front of them
- Gesture back so they know you saw
Show answer
Answer: B. Get out of the way; avoid eye contact
Make every effort to get out of their way, do not make eye contact, and report them if you can safely.
Question 14 of 25
About how far ahead can you see with low beam headlights?
- About 50 feet
- About 500 feet
- About 250 feet
- About 1,000 feet
Show answer
Answer: C. About 250 feet
Low beams show about 250 feet ahead. High beams show about 350 to 500 feet.
Question 15 of 25
When should you dim your high beams?
- Only when the other driver flashes you
- Only when you are driving in a town
- Within 500 feet of an oncoming or leading vehicle
- Within 100 feet of any other vehicle
Show answer
Answer: C. Within 500 feet of an oncoming or leading vehicle
Dim your lights within 500 feet of an oncoming vehicle and when following another vehicle.
Question 16 of 25
You feel very sleepy while driving at night. What is the only safe cure?
- Turn the radio up loud
- Open the window for air
- Get off the road and sleep
- Drink a strong coffee
Show answer
Answer: C. Get off the road and sleep
Sleep is the only safe cure for being sleepy. Stop driving.
Question 17 of 25
What is the best advice for driving in heavy fog?
- Use high beams so you can see farther
- Follow the tail lights ahead closely
- Speed up to get through it quickly
- Don't drive; wait at a rest area until it clears
Show answer
Answer: D. Don't drive; wait at a rest area until it clears
If you can, don't drive in fog. If you must, slow down before entering it and use low beams and fog lights.
Question 18 of 25
What should you know about tire chains before winter driving?
- One chain is enough for any truck
- Learn to put them on when the storm starts
- Carry enough, plus extra cross-links, and practice
- Chains are only needed on dry roads
Show answer
Answer: C. Carry enough, plus extra cross-links, and practice
Carry enough chains and extra cross-links, check them for broken hooks and worn links, and learn to put them on before you need them.
Question 19 of 25
Why is an exhaust leak dangerous in winter?
- It makes the heater run too hot
- Carbon monoxide can enter the cab
- It lowers the pressure in the tires
- It freezes the fuel in the lines
Show answer
Answer: B. Carbon monoxide can enter the cab
Exhaust leaks can let carbon monoxide into the cab. This gas causes sleepiness and can kill.
Question 20 of 25
Your brakes got wet in heavy rain. How can you dry them?
- Stop and wait an hour for them to air dry
- Pump the brakes quickly while parked
- Brake lightly while driving slowly in a low gear
- Brake hard several times at highway speed
Show answer
Answer: C. Brake lightly while driving slowly in a low gear
Slow down, use a low gear and gently apply the brakes to heat and dry them.
Question 21 of 25
In very hot weather, how often should you check your tires?
- Only at the start of the trip
- Every 500 miles
- Every 2 hours or every 100 miles
- Once a day
Show answer
Answer: C. Every 2 hours or every 100 miles
Heat raises tire pressure and temperature. Inspect tires every 2 hours or every 100 miles in hot weather.
Question 22 of 25
A tire is too hot to touch. What should you do?
- Spray it with cold water and drive on
- Let some air out
- Stay stopped until it cools off
- Keep driving to cool it with air
Show answer
Answer: C. Stay stopped until it cools off
Wait until a hot tire cools. Do not let air out, because the pressure will be too low when the tire cools.
Question 23 of 25
About how long does a typical tractor-trailer need to clear a single railroad track?
- At least 14 seconds
- About 7 seconds
- More than 1 minute
- About 3 seconds
Show answer
Answer: A. At least 14 seconds
A typical tractor-trailer needs at least 14 seconds to clear a single track and more than 15 seconds for a double track.
Question 24 of 25
What must you never do while driving across railroad tracks?
- Drive in a low gear
- Keep moving
- Shift gears
- Look both ways
Show answer
Answer: C. Shift gears
Never change gears while crossing the tracks. You could stall on them.
Question 25 of 25
Which vehicles must stop 15 to 50 feet before a railroad crossing?
- Buses with passengers and some hazmat vehicles
- Only school buses carrying students
- Only vehicles over 80,000 pounds
- Only vehicles that have air brakes
Show answer
Answer: A. Buses with passengers and some hazmat vehicles
Federal rules require buses with passengers and vehicles carrying certain hazardous materials to stop 15 to 50 feet from the tracks.

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