Free Missouri CDL practice test online
Take a free Missouri CDL practice exam online with clear explanations—no sign-up. Coverage includes general knowledge, vehicle systems, combination vehicles, cargo, and endorsements. Then verify current requirements with Missouri Driver License Bureau.
Missouri Driver License Bureau gives the general knowledge test as 50 questions, and federal law sets the bar at 80% correct on every knowledge test. You must also hold a commercial learner’s permit for 14 days before the skills test.
New to the knowledge test? CDL endorsements explained · One-week study plan
Requirements before you test
Missouri CDL test requirements
Commercial licensing is largely federal. Any figure above credited to a 49 CFR section applies in every state — see 49 CFR 383.135(a)(1) and 49 CFR 383.25(e). A figure credited to Missouri Driver License Bureau is Missouri’s own, and may be stricter than the federal floor. Test length, fees, and scheduling are set by Missouri Driver License Bureau (official source).
Entry-Level Driver Training comes first
Since February 7, 2022, a new Class A or Class B CDL, a class upgrade, or a first passenger, school bus, or hazardous materials endorsement requires training from a provider on the FMCSA Training Provider Registry (49 CFR 380.600). Practice questions are study material and do not satisfy that requirement.
FMCSA Training Provider RegistryYou need a Missouri licence first
A commercial learner’s permit only counts if you already hold an ordinary licence from the same state (49 CFR 383.25(a)(2)). The Missouri non-commercial knowledge test runs 25 questions and needs 20 correct, with permits issued from age 15.
Missouri permit practice testWhat you will practice
Build coverage topic by topic.
Each question carries a topic, difficulty, explanation, and source section so your review has context.
Sample questions
5 Missouri CDL practice questions
Try these Missouri sample questions now — each shows the correct answer with a plain-language explanation and a source section. The full 600-question bank is in the practice run.
1. In a dual air brake system, one system typically operates:
- AOnly the horn
- The regular brakes on one set of axles while the other system operates the remaining axle brakes
- COnly the trailer lights
- DOnly the parking lights
Answer: The regular brakes on one set of axles while the other system operates the remaining axle brakes. Both systems usually supply trailer air. Know which gauges show primary and secondary pressure.
Source: Commercial Driver License Manual — Air brakes — dual air brakes
2. Compared with a fully loaded truck, an empty truck generally:
- Needs greater stopping distance because it has less traction
- BHas identical braking performance
- CCannot skid
- DStops in a shorter distance
Answer: Needs greater stopping distance because it has less traction. Heavy-vehicle brakes, tires, and suspension are designed for a loaded vehicle. Empty trucks have less traction and often need more distance to stop.
Source: Commercial Driver License Manual — Driving safely — vehicle weight and stopping
3. Baffled tanks are generally safer than unbaffled tanks for liquid surge because baffles:
- ARemove the need for smooth braking
- BEliminate all liquid movement
- Slow forward-and-back surge while the liquid still moves somewhat
- DMake the tank illegal for food products always
Answer: Slow forward-and-back surge while the liquid still moves somewhat. Even with baffles, brake and accelerate smoothly—surge still affects handling on partially filled tanks.
Source: Commercial Driver License Manual — Tank vehicles — baffled vs unbaffled
4. Even with baffles, side-to-side surge can still:
- AEmpty the tank
- BNever occur
- Cause a rollover in a sudden lane change or ramp curve
- DIncrease traction
Answer: Cause a rollover in a sudden lane change or ramp curve. Baffles mainly slow longitudinal surge. Lateral surge remains a rollover risk—slow before turns.
Source: Commercial Driver License Manual — Tank vehicles — baffled tanks
5. Before backing a combination, you should:
- ARely only on the backup camera if equipped
- Get out and check the path for people and obstacles
- CSound the horn once and reverse immediately
- DDisconnect the emergency line
Answer: Get out and check the path for people and obstacles. Walk the path, agree on hand signals with a helper, and re-check if you wait before moving.
Source: Commercial Driver License Manual — Combination vehicles — backing safely
CDL knowledge areas
Classes and endorsements, organized.
Each area below scopes the reviewed question bank to one knowledge test. The material is federal, so it applies in Missouri just like everywhere else — the endorsement guide explains how the codes fit together.
The foundation for commercial driving: inspections, space, speed, communication, hazards, and safe operation.
- Pre-trip inspection
- Space and speed management
- Railroad crossings
- Emergency procedures
Understand air-brake components, inspections, warning devices, stopping distance, and controlled braking.
- Dual air systems
- Low-air warnings
- Brake lag and fade
- Applied-leak and static checks
Prepare for safe coupling, inspection, turning, backing, and handling of tractor-trailer combinations.
- Fifth-wheel inspection
- Coupling and uncoupling
- Off-tracking
- Trailer skid prevention
Study hazard communication, shipping papers, placards, loading rules, parking, and emergency response responsibilities.
- Hazard classes
- Placards and labels
- Shipping papers
- Loading and segregation
Learn how liquid surge, outage, bulkheads, and high centers of gravity change vehicle handling.
- Liquid surge
- Outage requirements
- Smooth braking
- Rollover prevention
Practice converter-dolly inspection, coupling order, rearward amplification, and stability principles.
- Coupling sequence
- Converter dollies
- Rearward amplification
- Space management
Prepare to inspect, load, and operate buses while keeping passengers, aisles, and exits safe.
- Vehicle inspection
- Passenger loading
- Emergency exits
- Prohibited practices
Review student loading, danger zones, mirrors, emergency procedures, and special railroad-crossing duties.
- Danger zones
- Student loading
- Mirror use
- Railroad crossings
More midwest practice
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Common questions
What this practice can—and cannot—tell you.