Missouri Combination Vehicles CDL Practice Test
Below are 25 exam-style questions for the Missouri Combination Vehicles 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.
- A Check that the trailer is stable on its landing gear
- B Disable the trailer parking brake
- C Connect the lines back to the tractor
- D Move the tractor far away immediately without checking
- A Stay in the right lane and swing the front of the tractor wide enough to clear the curb without inviting cars to pass on the right
- B Turn from the left lane
- C Use the shoulder
- D Stop traffic by signaling left
- A Be open
- B Be loose
- C Be missing
- D Be closed around the shank of the kingpin (not on the head)
- A All of the above
- B Backing too fast
- C Coupling with the trailer too high
- D Failure to grease
- A Cracks in the kingpin
- B Misalignment between tractor and trailer
- C All of the above
- D Loose or missing fifth-wheel mounting bolts
- A Loaded
- B Too high — it can damage the kingpin or skip over the fifth wheel
- C Empty
- D Properly chocked
- A Drain the air tanks
- B Disconnect the electrical line first
- C Honk the horn
- D Lower the trailer landing gear and chock the trailer wheels
- A Triangular, green, marked SERVICE
- B Round, blue, marked TRACTOR
- C Octagonal, red, marked TRAILER AIR SUPPLY
- D Square, white, marked CHARGE
- A Stopping distances increase and the trailer can swing
- B No effect on safety
- C Stopping distances are normal
- D Steering becomes easier
- A Use only mirrors
- B Back at full speed
- C GOAL — Get Out And Look — and walk around the trailer first
- D Have the dispatcher in the cab
- A Stop suddenly
- B Spin out
- C Roll over before sliding
- D Lose engine power
- A Drain the wet tank
- B Drive away immediately
- C Charge the trailer brakes by setting the trailer air supply control
- D Pump the brakes 10 times
- A Engine oil leaks
- B Cargo placement
- C Cuts, abrasions, and worn seals
- D Loose lug nuts only
- A Sliding sideways
- B Loss of traction
- C Driving off the road
- D The trailer wheels follow a tighter arc than the tractor wheels in a turn
- A Accelerate
- B Apply the trailer hand valve harder
- C Release the brakes to allow the trailer wheels to roll again, then steer
- D Disconnect the air supply
- A Its center of gravity is high
- B It uses air brakes
- C It is shorter than a straight truck
- D Its tires are wider
- A Released and visible after coupling
- B Tied with rope
- C Removed before driving
- D Locked and the safety latch in place after coupling
- A Listening to the brake light
- B Asking a mechanic
- C Pressing the pedal once at startup
- D Performing the seven-step air-brake check before each trip
- A The trailer to come uncoupled
- B Engine damage
- C Tire wear only
- D Rust on the cab
- A Driving too fast for conditions and/or too closely
- B Engine failure
- C Worn out tires
- D Cargo movement
- A Steering wander only
- B Engine knocking
- C Pulling, sticking, or unusual feel as you apply the brakes
- D Smoke from the cab
- A Loaded last
- B Last
- C First (closest to the tractor)
- D Either position is fine
- A It is illegal in some states
- B It is fine if you are careful
- C It can damage the cab and the trailer (cab corner crush)
- D It is the standard procedure
- A Replaces the fifth wheel on the tractor
- B Is part of the tractor
- C Is used to convert a semitrailer into a full trailer for towing in combination
- D Is used only when triple-towing
- A Test the trailer brakes
- B Apply trailer brakes momentarily
- C Hold the vehicle when parking
- D Both for parking and to prevent jackknife
Study tips for the Missouri Combination Vehicles exam
The Combination Vehicles 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 Combination Vehicles 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 Combination Vehicles.
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 Combination Vehicles 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 Combination Vehicles 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 General Knowledge · MO Air Brakes · 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.