Gross Combination Weight Rating

MO · GK Endorsement

Missouri General Knowledge CDL Practice Test

Below are 25 exam-style questions for the Missouri General Knowledge CDL knowledge test, modeled on the FMCSA-aligned content used by the Missouri Department of Revenue. Try to answer each question on your own before reading the answer key directly under it. The questions and answer choices are shuffled deterministically per state and endorsement, so the order will stay the same on repeat visits — that lets you genuinely measure your improvement.

Heads up: this is a study tool, not a graded exam. Cover the answer with your hand or a sheet of paper for an honest practice run, then re-read the explanations for any questions you missed. Aim for 22 out of 25 or better, three times in a row, before scheduling the real exam.

Question 1 of 25

You may not drive a CMV with a blood-alcohol concentration of:

A 0.08% or higher
B 0.04% or higher
C 0.10% or higher
D Any detectable amount above 0.00%

Correct answer: B

0.04% is the regulatory limit for CMV operation. A detectable amount under that triggers an out-of-service order but is not necessarily a DUI conviction.

Question 2 of 25

Black ice is most likely on:

A Roads in direct sunlight
B Bridges and overpasses
C Concrete pavement only
D Gravel surfaces

Correct answer: B

Bridges and overpasses freeze first because cold air circulates above and below them. They are the most-asked test scenario for sudden ice.

Question 3 of 25

A driver should secure cargo so it:

A Looks neat from the outside
B Is loaded in the order it will be delivered
C Fills the trailer floor edge to edge
D Cannot shift on stops, starts, or turns and is within axle weight limits

Correct answer: D

The legal standard is securement against forces during normal driving conditions plus an emergency stop, and within axle and total weight limits.

Question 4 of 25

What does GVWR stand for?

A Government Vehicle Weight Regulation
B Gross Vehicle Width Rating
C Gross Vehicle Weight Rating
D General Vehicle Weight Reading

Correct answer: C

GVWR is the maximum weight the manufacturer says a single vehicle can safely weigh, including itself plus its load.

Question 5 of 25

Which of the following is NOT part of a pre-trip inspection?

A Adjusting the trailer brakes individually
B Walking around the vehicle and checking lights
C Testing the service and parking brakes
D Checking the engine compartment

Correct answer: A

Adjusting brakes is a maintenance task done by qualified personnel, not a pre-trip step. The driver checks for proper operation, not adjustment.

Question 6 of 25

Which is true about driving in rain?

A High beams improve visibility in heavy rain
B Roads are most slippery just after rain begins, when water mixes with road oil
C It is safe to drive at the posted speed limit
D Tire chains are required by federal law

Correct answer: B

The first few minutes of rain mix with oil and grime on the road and create the slipperiest conditions. Slow down and increase following distance.

Question 7 of 25

A CDL is required to operate a single vehicle with a GVWR of:

A 20,000 lbs or more
B 10,001 lbs or more
C 40,000 lbs or more
D 26,001 lbs or more

Correct answer: D

Single vehicles at or above 26,001 lbs GVWR (Class B) require a CDL. Class A applies to combinations at or above 26,001 lbs GCWR with a trailer over 10,000 lbs.

Question 8 of 25

A Class C CDL is required to drive:

A Tractor-trailers under 26,001 lbs GCWR
B Vehicles designed to carry 16+ passengers including the driver, or that require hazmat placards
C Class A combinations only
D Any vehicle over 26,001 lbs

Correct answer: B

Class C covers vehicles that don't meet Class A or B but are designed to carry 16 or more passengers (including the driver) or carry placarded amounts of hazardous materials.

Question 9 of 25

Skids are most often caused by:

A Properly working brakes
B Manual transmissions
C Old tires
D Driving too fast for conditions

Correct answer: D

The dominant cause of skids identified by the FMCSA is driving too fast for the road or weather. Sudden steering, hard braking, or hard acceleration usually triggers them.

Question 10 of 25

Hydroplaning is most likely when:

A You brake hard on dry pavement
B Tires are over-inflated
C Tires lose contact with the road on a film of water
D Roads are dry but hot

Correct answer: C

Hydroplaning happens when tires ride on top of standing water at speed. Reduce risk by slowing down, keeping tires properly inflated and tread depth adequate.

Question 11 of 25

A driver must report any accident involving a CMV to the carrier within:

A 1 hour
B A reasonable time, before going off duty
C 24 hours
D 7 days

Correct answer: B

FMCSA rules require notification of the motor carrier in a reasonable time — most policies treat that as before going off duty.

Question 12 of 25

What is the most important reason for doing a vehicle inspection?

A To reduce tire wear
B To improve fuel economy
C To meet your dispatcher's schedule
D Safety for yourself and other road users

Correct answer: D

Federal rules and the FMCSA model manual list safety as the single most important reason for a pre-trip inspection. Mechanical defects discovered before the trip cannot kill anyone on the highway.

Question 13 of 25

When you double your speed, your stopping distance approximately:

A Doubles
B Quadruples
C Stays the same
D Triples

Correct answer: B

Braking distance increases roughly with the square of speed; doubling speed quadruples the braking distance. Reaction distance only doubles, but the total grows quickly.

Question 14 of 25

The most important hand position on the steering wheel is:

A 12 and 6
B One hand at 12
C 10 and 2 (or 9 and 3)
D Both hands at the bottom

Correct answer: C

A balanced grip at 10-and-2 or 9-and-3 gives the most control. One-handed and bottom-of-wheel positions reduce reaction time.

Question 15 of 25

A vehicle's "no-zone" is:

A The area immediately next to it where other drivers are hidden in your blind spots
B The fuel tank area
C A federal speed restriction
D The area in front of the steer axle

Correct answer: A

No-zones are the four blind-spot areas (front, rear, and both sides) where smaller vehicles are difficult or impossible to see in your mirrors.

Question 16 of 25

Which of the following is the correct order for the seven-step pre-trip air-brake check (last steps shown)?

A Test the low-air warning then drive
B Test the service brake then the parking brake
C Test the parking brake then the service brake
D Test only the air-leak rate

Correct answer: C

In the standard FMCSA seven-step procedure, the parking brake is tested before pulling away, then the service brake stop is the final step.

Question 17 of 25

When approaching a railroad crossing in a CMV that is not required to stop, you should:

A Honk and proceed
B Always come to a full stop regardless of traffic
C Cross at maximum speed to get over quickly
D Slow down, look, listen, and be prepared to stop

Correct answer: D

Even when not required by class to stop, you must always be prepared to stop. Buses, hazmat, and certain other vehicles must stop every time.

Question 18 of 25

A driver who refuses to take a required drug or alcohol test is treated as if they:

A Did not take the test, with no consequence
B Took the test and passed
C Took the test and failed
D Need to take it again later

Correct answer: C

Refusal is a federal CDL disqualification with the same consequences as a positive test.

Question 19 of 25

How does ABS help in an emergency stop?

A It increases brake pressure automatically
B It prevents wheel lockup so the driver can keep steering
C It always stops the vehicle in a shorter distance
D It applies the parking brake

Correct answer: B

ABS keeps the wheels rolling so steering control is preserved. It is not a shorter-distance device.

Question 20 of 25

Which is required when stopping on the side of a level, straight, two-lane road?

A Three reflective triangles: 10 ft, 100 ft, and 200 ft toward approaching traffic
B A spotter walking 1,000 ft up the road
C One reflective triangle within 10 feet
D A flare burning constantly

Correct answer: A

On a level straight road, place triangles 10 feet behind the vehicle, 100 feet, and 200 feet to the rear in the direction of approaching traffic.

Question 21 of 25

When should you use four-way flashers?

A Whenever you feel like it
B Only at night
C When you are stopped or moving slowly enough to be a hazard
D Only on the highway

Correct answer: C

Four-ways are for vehicles stopped on or near the road or moving so slowly that they are a hazard.

Question 22 of 25

The minimum tread depth for steer-axle tires is:

A 2/32 inch
B 6/32 inch
C 4/32 inch
D 1/32 inch

Correct answer: C

Steer tires must have at least 4/32 inch in every major groove. Other tires require at least 2/32 inch.

Question 23 of 25

Which is true about driving in mountains?

A Heavy vehicles can slow down sharply on grades
B All of the above
C Engine braking helps keep speed under control
D Brakes alone are not designed to hold a heavy vehicle on a long downgrade

Correct answer: B

Mountain driving combines all three. Use of low gears, engine braking, and short, moderate service-brake applications is the safe combination.

Question 24 of 25

When approaching a steep downgrade, the basic safe-driving rule is:

A Use the parking brake intermittently
B Stay in high gear
C Coast in neutral
D Select a lower gear before starting down

Correct answer: D

Get into a low gear before the descent so the engine helps hold the vehicle back.

Question 25 of 25

GCWR stands for:

A Gross Cargo Weight Rating
B General Carrier Weight Rating
C Government Combination Weight Reading
D Gross Combination Weight Rating

Correct answer: D

GCWR is the maximum allowable weight of a power unit plus a towed unit, including all cargo. It determines whether a license is Class A.

Study tips for the Missouri General Knowledge exam

The General Knowledge portion of the Missouri CDL exam is graded out of the bank of questions the Missouri Department of Revenue draws from each year. While the exact bank is not published, every question is sourced from the General Knowledge chapter of the Missouri CDL handbook, which itself is derived from the FMCSA Model Commercial Driver's License Manual. That means studying our practice tests, reading the corresponding handbook chapter, and re-reading the parts you got wrong is genuinely the most efficient route to a first-time pass.

Most successful applicants follow a simple cycle: take the practice test cold, write down every question you missed, open the matching chapter of the official Missouri handbook, re-read the section that contains the right answer, then re-take the practice test 24 to 48 hours later. The 24-hour delay matters — sleep is when your brain commits new information to long-term memory, and CDL knowledge questions reward that kind of consolidated learning rather than cramming.

Pay particular attention to questions that include qualifier words like always, never, only, primary, or most. CDL test writers love to flip the right answer with a single qualifier. When two answer choices look almost identical, pay attention to the verb (is it must, should, or may?) and to any numbers (14 days, 100 air miles, 8 hours, 70/8 split). On endorsement tests in particular, watch for trick framing where a true statement about a different endorsement is offered as the "correct" answer to a question that is actually about General Knowledge.

Test-day logistics matter too. Bring photo ID, your Social Security card or birth certificate, your medical examiner's certificate (DOT card), and proof of state residency if you haven't already submitted those documents. The Missouri Department of Revenue will not let you sit for the knowledge exam without your documentation, and most offices charge an additional fee for re-attempts. Arrive early — the wait at most CDL testing offices runs 30 to 60 minutes — and silence your phone before the exam begins.

Finally, keep your General Knowledge fundamentals sharp even when you're focused on the General Knowledge exam. Many states administer multiple knowledge tests in a single sitting, and questions on weight definitions (GVWR, GCWR, GAWR), stopping distance, and the pre-trip inspection routine show up across endorsements. If you're unsure on the basics, sit a fresh Missouri General Knowledge practice test before scheduling the real exam.

Next steps

Missed more than four questions? Re-read the General Knowledge study guide and the matching chapter in the official Missouri CDL handbook. Then come back and re-take the test. Once you can score 22 of 25 or higher on three runs in a row, you're in good shape to schedule the real exam at your local Missouri Department of Revenue office.

Already comfortable with this endorsement? Drill another: MO Air Brakes · MO Combination Vehicles · MO Hazardous Materials · MO Passenger · MO School Bus · MO Tank Vehicle · MO Doubles / Triples

New to the CDL process in Missouri? Read How to apply for a CDL in Missouri for the document checklist and step-by-step timeline.