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Illinois CDL practice test

Getting a commercial driver's licence in Illinois starts with the CDL knowledge tests. The content is federal: every state, Illinois included, writes its tests from the FMCSA CDL manual, so the general knowledge test has 50 questions, the endorsement tests have 20 to 30, and the passing score is 80% on each. The Illinois driver licensing agency administers the test; the rules behind it are published by the FMCSA. Try the free Illinois CDL practice questions below, then pick a full test.

Free Illinois CDL practice questions

Five questions from the general knowledge, air brakes and combination vehicles banks, the three tests most Illinois Class A applicants take first. Show the answer to read the explanation.

  1. When the temperature drops, which part of the road freezes first?

    • Uphill grades
    • Bridges
    • Dirt shoulders
    • Sections with fresh asphalt
    Show answer
    Answer: B. Bridges

    Cold air reaches a bridge from above and below, so bridges ice up before the road around them. Be especially careful on bridges when it is near freezing.

    Source: FMCSA CDL Manual, Section 2.6.2 (Identifying Slippery Surfaces)

  2. Why is the road especially slippery right after it starts to rain?

    • The rain cools the tires too quickly
    • Rain makes the asphalt soften
    • The water mixes with oil and dirt on the surface and forms a slick film until more rain washes it away
    • Traffic slows down and blocks the road
    Show answer
    Answer: C. The water mixes with oil and dirt on the surface and forms a slick film until more rain washes it away

    In the first minutes of rain, oil and grime on the pavement float to the surface and make it very slick. Heavier rain eventually washes this film off.

    Source: FMCSA CDL Manual, Section 2.6.2 (Identifying Slippery Surfaces)

  3. If your vehicle starts to hydroplane, you should:

    • Brake hard to stop quickly
    • Speed up to push through the water
    • Turn the wheel sharply to regain grip
    • Release the accelerator and push in the clutch; do not use the brakes
    Show answer
    Answer: D. Release the accelerator and push in the clutch; do not use the brakes

    Hydroplaning means the tires are riding on water. Taking your foot off the gas and pushing in the clutch lets the wheels slow and turn freely so they can regain contact with the road.

    Source: FMCSA CDL Manual, Section 2.6.2 (Hydroplaning)

  4. At night or in fog, your speed should allow you to:

    • Stop within the distance you can see ahead
    • Keep up with the posted speed limit
    • Pass slower traffic quickly
    • Reach your destination on schedule
    Show answer
    Answer: A. Stop within the distance you can see ahead

    You cannot avoid a hazard you have not seen. If you are driving so fast that your stopping distance is longer than your sight distance, you are overdriving your headlights.

    Source: FMCSA CDL Manual, Section 2.6.3 (Speed and Distance Ahead)

  5. When driving through a work zone, you should:

    • Keep the highway speed limit so you do not block traffic
    • Reduce speed and be ready to stop; use flashers or brake lights to warn drivers behind you if you are going slowly
    • Move to the far left lane and pass the work vehicles
    • Turn off your headlights so you do not blind the workers
    Show answer
    Answer: B. Reduce speed and be ready to stop; use flashers or brake lights to warn drivers behind you if you are going slowly

    Speeding traffic is the leading cause of injury and death in work zones. Slow down, watch for workers and equipment, and warn the traffic behind you when you are moving slowly.

    Source: FMCSA CDL Manual, Section 2.6.6 (Work Zones)

Every CDL test for Illinois drivers

Each page has ten free sample questions, the real question count, the 80% pass mark and what the test covers.

How the Illinois CDL knowledge test works

You take the general knowledge test first; it is required for every CDL class. Class A drivers add the combination vehicles test. Almost everyone takes the air brakes test, because skipping it puts an air brake restriction on the licence. Endorsements (hazmat, tanker, doubles/triples, passenger, school bus) each have their own knowledge test. Pass the tests and you hold a commercial learner's permit; the skills test in a truck comes later.

Fees, appointment rules and test centre locations are set by Illinois and change over time, so check the state driver licensing agency before you go. What does not change is the content, and that is what PassRig drills.

Illinois CDL test questions

How many questions are on the Illinois CDL test?

The Illinois CDL general knowledge test follows the federal model: 50 questions, 40 correct to pass. Endorsement tests are shorter: air brakes 25, hazmat 30, and combination vehicles, tanker, doubles/triples, passenger and school bus 20 each.

What is the passing score on the Illinois CDL permit test?

80% on every knowledge test, the same pass mark used across the United States.

Where do I take the CDL knowledge test in Illinois?

At the Illinois state driver licensing agency (the DMV, DOT or equivalent). Check its website for locations, appointments and current fees; the test content itself comes from the FMCSA CDL manual.

Does PassRig have Illinois CDL practice questions?

Yes. Pick Illinois in the app and you get practice sets and mock exams built from the knowledge test content your state uses, with the real counts and the 80% line.

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