Illinois CDL General Knowledge Practice Test

The Illinois CDL General Knowledge test is a multiple-choice knowledge test you take for your commercial learner's permit. Illinois Secretary of State, Driver Services Department says you need 80% to pass (source).

Last updated Oct 15, 2026. FirstTry CDL is a CDL permit test prep site by Hive Asset Group, LLC.

By Scott Wilder, Editor

Last reviewed against the Illinois CDL manual on October 15, 2026

Scott Wilder on X | scottwilderhq.com

FirstTry CDL is a CDL permit test prep site by Hive Asset Group, LLC. It offers free exam-style practice tests built from the official CDL manual. FirstTry CDL is not affiliated with any DMV, FMCSA or government agency. Practice questions are exam-style questions built from the official CDL manual, not actual test questions.

Illinois CDL permit facts

What	What Illinois says	Source
General Knowledge pass mark	80%	Official page
General Knowledge test questions	30	Official page
CLP fee (adding a CLP to an Illinois non-CDL license, or renewing an original CLP)	$50	Official page
CLP fee (current CDL holder upgrading class or adding an endorsement)	$5	Official page
CLP validity	One year. An original CLP expires one year from the date it is first issued.	Official page
Test languages	CDL knowledge tests are given in English only. You can ask for the audio format, where the computer reads the test. After trying audio, you can ask facility management about an oral test read by staff.	Official page

20 question General Knowledge practice test

1. How do you stop heavy bleeding?
1. A. Pour water on it
2. B. Move the person quickly
3. C. Wait for the police
4. D. Apply direct pressure to the wound
Show answer
Answer: D. Apply direct pressure to the wound
Direct pressure on the wound stops heavy bleeding.
From the official CDL manual, section 2.20.3.
2. You walk up to your vehicle to start an inspection. What should you look for under it?
1. A. Fresh oil, coolant, grease, or fuel leaks
2. B. Only mud and dirt
3. C. Only the spare tire
4. D. Only a sign of the last driver
Show answer
Answer: A. Fresh oil, coolant, grease, or fuel leaks
The manual says to look under the vehicle for fresh oil, coolant, grease, or fuel leaks.
From the official CDL manual, section 2.1.5.
3. A car is following you too closely. What is a good response?
1. A. Speed up to get away from it
2. B. Brake hard to make it back off
3. C. Flash your brake lights over and over
4. D. Increase your following distance
Show answer
Answer: D. Increase your following distance
More room in front helps you avoid sudden speed or direction changes.
From the official CDL manual, section 2.7.2.
4. Which step helps prevent drowsiness before a trip?
1. A. Take a cold tablet or antihistamine before leaving
2. B. Plan to drive alone so nothing distracts you
3. C. Schedule the trip for hours when you are normally awake
4. D. Eat a large meal before you start
Show answer
Answer: C. Schedule the trip for hours when you are normally awake
Driving during your normal waking hours lowers your drowsy-driving risk.
From the official CDL manual, section 2.11.2.
5. You will carry heavy pieces of metal. What should you do about securement?
1. A. Use the same tie-downs you use for any load
2. B. Skip tie-downs, since heavy items stay put
3. C. Use ropes only
4. D. Find out the special requirements for securing them
Show answer
Answer: D. Find out the special requirements for securing them
The manual says heavy metal pieces have special securement requirements you should learn.
From the official CDL manual, section 3.3.2.
6. With "progressive" shifting, how does the shift rpm change as you move up in the gears?
1. A. It becomes lower
2. B. It becomes higher
3. C. It stays the same in every gear
Show answer
Answer: B. It becomes higher
In progressive shifting the rpm at which you shift becomes higher as you move up in the gears.
From the official CDL manual, section 2.3.1.
7. At 55 mph, how far do you travel during your perception time?
1. A. 61 feet
2. B. 216 feet
3. C. 142 feet
4. D. 419 feet
Show answer
Answer: C. 142 feet
The manual says perception distance at 55 mph is 142 feet.
From the official CDL manual, section 2.6.1.
8. When do you need a hazmat endorsement to drive a vehicle with hazardous materials?
1. A. Any time you carry any hazardous material
2. B. When the vehicle requires placards
3. C. Only when you carry explosives
4. D. Only on interstate trips
Show answer
Answer: B. When the vehicle requires placards
If the vehicle needs placards, you must have the hazmat endorsement.
From the official CDL manual, section 2.23.3.
9. You start on a hill in a tractor-trailer. What can help you keep from rolling back?
1. A. The four-way flashers
2. B. The trailer brake hand valve
3. C. The horn
4. D. The engine retarder
Show answer
Answer: B. The trailer brake hand valve
The manual says the hand valve can be applied to keep from rolling back.
From the official CDL manual, section 2.2.1.
10. Which trick does the manual say to avoid with a tailgater?
1. A. Signaling early
2. B. Slowing down gradually
3. C. Flashing your brake lights
4. D. Increasing your following distance
Show answer
Answer: C. Flashing your brake lights
The manual says to avoid tricks like flashing your brake lights.
From the official CDL manual, section 2.7.2.
11. A modern truck climbs a hill in a high gear. Which gear may it need going down?
1. A. Always the same gear used to climb
2. B. A lower gear than it used to climb
3. C. Always a higher gear than it used to climb
4. D. Neutral
Show answer
Answer: B. A lower gear than it used to climb
Modern trucks have less friction and drag, so they may need lower gears going down.
From the official CDL manual, section 2.16.2.
12. You left the road and the shoulder is clear. What should you do?
1. A. Stay on the shoulder until you come to a stop
2. B. Keep driving on the shoulder and do not stop
3. C. Brake hard right away
4. D. Return to the road as fast as you can
Show answer
Answer: A. Stay on the shoulder until you come to a stop
If the shoulder is clear, stay on it until the vehicle has stopped.
From the official CDL manual, section 2.17.1.
13. In stab braking, what do you do when the wheels lock up?
1. A. Release the brakes, then press fully again once the wheels roll
2. B. Keep pressing the pedal harder
3. C. Release the brakes and wait several seconds
4. D. Steer sharply to the side
Show answer
Answer: A. Release the brakes, then press fully again once the wheels roll
Stab braking means braking fully, releasing when wheels lock, and braking again when they roll.
From the official CDL manual, section 2.17.2.
14. How should you adjust space when driving on snow and ice?
1. A. Keep a longer following distance
2. B. Follow closely to stay warm
3. C. Keep the same following distance
4. D. Drive alongside other vehicles
Show answer
Answer: A. Keep a longer following distance
Keep a longer following distance and do not drive alongside others.
From the official CDL manual, section 2.13.2.
15. A driver at 55 mph is blinded by glare for two seconds. How far does the vehicle travel?
1. A. About the length of one car
2. B. About the length of a tractor-trailer
3. C. More than half the length of a football field
4. D. More than two football fields
Show answer
Answer: C. More than half the length of a football field
At 55 mph, two seconds of glare blindness covers more than half a football field.
From the official CDL manual, section 2.11.2.
16. What is the minimum tread depth in every major groove of front tires?
1. A. 2/32 inch
2. B. 1/32 inch
3. C. 4/32 inch
4. D. 6/32 inch
Show answer
Answer: C. 4/32 inch
Front tires need at least 4/32 inch of tread in every major groove.
From the official CDL manual, section 2.13.1.
17. When is a road especially slippery in the rain?
1. A. After it has rained for several hours
2. B. Just after the rain stops
3. C. Right after the rain begins
4. D. Only when the road is flooded
Show answer
Answer: C. Right after the rain begins
At the start of a rain, water mixes with oil on the road and makes it very slippery.
From the official CDL manual, section 2.6.2.
18. Which knowledge test must every CDL applicant take?
1. A. The air brakes test
2. B. The combination vehicles test
3. C. The general knowledge test
4. D. The passenger transport test
Show answer
Answer: C. The general knowledge test
The general knowledge test is taken by all applicants.
From the official CDL manual, section 1.1.1.
19. You expect to be hungry on a long drive. What does the manual suggest?
1. A. Eat while driving
2. B. Leave early so you can stop to eat
3. C. Eat only on straight roads
4. D. Eat only at low speed
Show answer
Answer: B. Leave early so you can stop to eat
Avoid eating while you drive. Leave early to allow time to stop to eat.
From the official CDL manual, section 2.9.6.
20. A front tire and a rear tire each have 3/32 inch of tread in every major groove. Which statement is true?
1. A. The rear tire meets the minimum, but the front tire does not
2. B. Both tires meet the minimum
3. C. Neither tire meets the minimum
4. D. The front tire meets the minimum, but the rear tire does not
Show answer
Answer: A. The rear tire meets the minimum, but the front tire does not
Front tires need 4/32 inch and other tires need 2/32 inch, so 3/32 inch is enough only for the rear tire.
From the official CDL manual, section 2.1.3.

Illinois CDL General Knowledge questions

What score do you need to pass the Illinois CDL General Knowledge test?

Illinois says you need 80% to pass the General Knowledge test.

Is the Illinois CDL General Knowledge test the same as other states?

The General Knowledge test is built on the same federal knowledge standards in every state, so the topics match the CDL manual. Illinois uses its own handbook: https://www.ilsos.gov/content/dam/publications/pdf_publications/dsd_cdl10.pdf

How much does a CDL permit cost in Illinois?

CLP fee (adding a CLP to an Illinois non-CDL license, or renewing an original CLP): $50.

What languages is the Illinois CDL knowledge test offered in?

CDL knowledge tests are given in English only. You can ask for the audio format, where the computer reads the test. After trying audio, you can ask facility management about an oral test read by staff.

Sources

https://www.ilsos.gov/content/dam/publications/pdf_publications/dsd_cdl10.pdf
https://www.ilsos.gov/departments/drivers/basicfees.html
https://www.ilsos.gov/departments/drivers/drivers-license/cdl/cdl.html
Manual sections used in this test: 1.1.1; 2.1.3; 2.1.5; 2.11.2; 2.13.1; 2.13.2; 2.16.2; 2.17.1; 2.17.2; 2.2.1; 2.20.3; 2.23.3; 2.3.1; 2.6.1; 2.6.2; 2.7.2; 2.9.6; 3.3.2

General Knowledge practice test in nearby states