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Free CDL Practice Test Online

Official exam: CDL General Knowledge

Take a free CDL practice test online: a full 50-question paper with every answer explained, no sign-up, scored by topic. The full 124-question bank and the timed simulator are $14.99 for 30 days.

First published: September 1, 2026Bank updated: September 1, 2026Published by CertQuestUSA · review process
TL;DR

CDL General Knowledge: a 124-question practice bank for the real CDL Permit & Endorsement Exams standard, 2 full papers of 50 questions each with no repeats, every question written to the regulation it comes from.

Where these questions come from

Every question in this bank cites a real source -- primarily FMCSA CDL Manual (77%) and 49 CFR (23%) of this exam's citations.

Take a full practice test free. 50 real questions built to the exam's domain weights, every answer explained, no sign-up required, with a domain-by-domain score at the end.
Start diagnostic
2
full papers, no repeats
50
questions per paper
124
questions in the bank
What this exam covers

Start with general knowledge, then choose the tests for your vehicle

  1. Answer the ten-question diagnostic without looking up the answers. Treat the result as a small sample, not a prediction that you will pass.
  2. Read the explanation and cited manual section for each mistake. Write down the decision or rule you missed, rather than memorizing an answer letter.
  3. Use your weakest domain to plan the next study session. Add air brakes and combination vehicles when they apply to the vehicle you intend to drive.

This is knowledge practice. It does not issue a permit, provide behind-the-wheel instruction or replace required entry-level driver training.

Official CDL manual · Editorial process and corrections

Continue studying: CDL Air BrakesCDL Combination Vehicles

See the CDL study path
5 real sample questions
What is the most important reason for performing a pre-trip inspection before every trip?
A. To satisfy your dispatcher that the truck left on time
B. To find problems that could cause a crash or breakdown before they happen on the road
C. To reduce the number of miles logged for the day
D. To avoid having to fill out any paperwork later
Show answer and reasoning

Correct answer: B. To find problems that could cause a crash or breakdown before they happen on the road

  • A: A pre-trip inspection has nothing to do with dispatch timing.
  • C: Inspection findings do not change logged mileage.
  • D: A pre-trip inspection actually creates required paperwork (the inspection report), not less of it.
Source: FMCSA CDL Manual §2.1.1
A roadside inspector determines that a commercial motor vehicle has a safety defect serious enough to be an immediate hazard. What is the inspector authorized to do under 49 CFR 396.9?
A. Issue a warning only, since only the motor carrier can pull a vehicle from service
B. Declare the vehicle "out of service" until the defect is corrected
C. Impound the vehicle permanently
D. Fine the driver but allow the vehicle to continue to the next scheduled stop
Show answer and reasoning

Correct answer: B. Declare the vehicle "out of service" until the defect is corrected

  • A: 396.9 gives the inspector authority to declare the vehicle out of service, not merely to warn.
  • C: Out-of-service means repaired and released, not permanent impoundment.
  • D: An out-of-service order prohibits further operation until the defect is fixed, not a fine-and-continue arrangement.
Source: 49 CFR 396.9
Under the federal tire tread depth standard, what is the minimum tread depth allowed in any major tread groove on a steering axle tire?
A. 1/32 inch
B. 2/32 inch
C. 4/32 inch
D. 6/32 inch
Show answer and reasoning

Correct answer: C. 4/32 inch

  • A: 1/32 inch is below the federal minimum for any position.
  • B: 2/32 inch is the minimum for tires on axles other than the steering axle.
  • D: 6/32 inch is deeper than the regulation requires, though additional depth is never unsafe.
Source: 49 CFR 393.75
What is the minimum tread depth required on non-steering axle tires of a commercial motor vehicle?
A. 1/32 inch
B. 2/32 inch
C. 3/32 inch
D. 4/32 inch
Show answer and reasoning

Correct answer: B. 2/32 inch

  • A: 1/32 inch is too shallow to meet the federal standard for any tire position.
  • C: 3/32 inch is not the regulatory threshold; the rule specifies 2/32 inch for non-steering tires.
  • D: 4/32 inch is the steering-axle minimum, not the standard for other axle positions.
Source: 49 CFR 393.75
Under 49 CFR 392.7, a driver may not operate a commercial motor vehicle unless satisfied that certain systems are in good working order. Which of the following is included in that pre-trip requirement?
A. The radio and cab air-conditioning system
B. Service brakes, trailer brake connections, parking brake, tires, lights, and mirrors
C. The cruise control set speed
D. The fuel economy displayed on the dashboard computer
Show answer and reasoning

Correct answer: B. Service brakes, trailer brake connections, parking brake, tires, lights, and mirrors

  • A: Comfort features like radio and A/C are not part of the 392.7 safety-systems check.
  • C: Cruise control settings are a convenience feature, not a listed safety system.
  • D: Fuel economy readouts are informational only, not a safety-critical system under 392.7.
Source: 49 CFR 392.7
Real-world data for this exam
Heavy and Tractor-Trailer Truck Drivers: real median wageMay 2025$58,640/yrUnsafe Drivingsince 2023-01-01609,590 violationsPart of the real CDL Driver career pathExplore ›
Related reading
How Many Times Can You Retake the CDL Permit Test? Real Rules by State ›CLP vs CDL: What’s the Real Difference, and How Long Do You Have to Wait? ›The Real CDL English Language Requirement in 2026, and Why It Now Puts Drivers Out of Service ›Online Training for Employees: Why Compliance Training Needs a Different Platform Than Onboarding Training ›

Frequently asked questions

Where can I take a free CDL practice test online?
Right here. CertQuestUSA's free CDL practice test online is a full 50-question practice paper built to the real exam's domain weights, with every answer explained, with no sign-up and no credit card, and shows your score by topic at the end. The full 124-question bank, with every answer explained and cited to the regulation it comes from, is $14.99 for a 30-day pass that never renews.
How many questions are on the CertQuestUSA CDL General Knowledge practice test?
124 questions total, split into 2 full papers of 50 each with no repeats across papers.
What topics does the CDL General Knowledge test cover?
13 domains, with the heaviest weight on Vehicle Inspection (14%), Basic Control & Shifting (10%), and Emergency Maneuvers & Skid Control (10%).
Where do CertQuestUSA's CDL General Knowledge questions come from?
Primarily FMCSA CDL Manual (77%) and 49 CFR (23%) of this bank's citations -- computed directly from this exam's own question sources, not a generic description.
Is there a free CDL General Knowledge practice test?
Yes -- one full 50-question practice paper built to the exam's domain weights, free with no sign-up, with every answer explained and a domain-by-domain score at the end.
Still need a CDL school, a DOT physical, or tuition help?
CDL Schools USA, our sister site, lists FMCSA-registered schools by state, paid training programs, DOT physical clinics, and WIOA and GI Bill funding.
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