Colorado Combination Vehicles CDL Practice Test
Below are 25 exam-style questions for the Colorado Combination Vehicles CDL knowledge test, modeled on the FMCSA-aligned content used by the Colorado Department of Revenue Division of Motor Vehicles. 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 Replaces the fifth wheel on the tractor
- B Is used only when triple-towing
- C Is part of the tractor
- D Is used to convert a semitrailer into a full trailer for towing in combination
- A Hand valves
- B Sensors at each wheel that release brake pressure when wheel lockup is detected
- C A separate compressor
- D Hydraulic brakes
- A Performing the seven-step air-brake check before each trip
- B Asking a mechanic
- C Pressing the pedal once at startup
- D Listening to the brake light
- A Carries electrical signals
- B Drains the wet tank
- C Sends supply air to the trailer reservoirs and controls the trailer emergency brakes
- D Operates the parking brake only
- A All of the above
- B Failure to grease
- C Backing too fast
- D Coupling with the trailer too high
- A Honk and accelerate
- B Cross in a low gear without shifting
- C Stop on the tracks if traffic ahead slows
- D Shift in the middle of the track
- A Connect the lines back to the tractor
- B Disable the trailer parking brake
- C Move the tractor far away immediately without checking
- D Check that the trailer is stable on its landing gear
- A Loose lug nuts only
- B Cargo placement
- C Engine oil leaks
- D Cuts, abrasions, and worn seals
- A Listen for a click
- B Honk the horn
- C Look at the locking jaws only
- D Tug the trailer with the trailer parking brakes set
- A The fifth wheel disengages
- B The tractor parking brake fails
- C The drive wheels lose traction and the tractor begins to slide
- D The trailer is too heavy
- A Brake balance is irrelevant
- B ABS prevents jackknife in all cases
- C Drive wheels never lock
- D Trailer wheels lock more often than drive wheels in panic stops
- A Stops only with parking brake
- B Stops faster than when loaded
- C Stops in the same distance
- D May actually take longer to stop because brakes are designed for the loaded weight
- A Disconnect the air supply
- B Apply the trailer hand valve harder
- C Release the brakes to allow the trailer wheels to roll again, then steer
- D Accelerate
- A Sends supply air to the trailer reservoirs
- B Drains the trailer reservoir
- C Carries electrical power
- D Sends air pressure to apply trailer service brakes
- A Last
- B Loaded last
- C First (closest to the tractor)
- D Either position is fine
- A It uses air brakes
- B Its tires are wider
- C It is shorter than a straight truck
- D Its center of gravity is high
- A Electrical connectors
- B Coupling devices for connecting tractor air lines to the trailer
- C Manual transmission shifters
- D Brake adjustment levers
- A By setting the red trailer-air-supply valve
- B By pulling out the red trailer-air-supply valve
- C By the trailer hand valve
- D By pushing in the red trailer-air-supply valve
- A Square, white, marked CHARGE
- B Octagonal, red, marked TRAILER AIR SUPPLY
- C Round, blue, marked TRACTOR
- D Triangular, green, marked SERVICE
- A Drain the wet tank
- B Pump the brakes 10 times
- C Drive away immediately
- D Charge the trailer brakes by setting the trailer air supply control
- A Use the shoulder
- B Turn from the left lane
- C 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
- D Stop traffic by signaling left
- A Lower the trailer landing gear and chock the trailer wheels
- B Honk the horn
- C Disconnect the electrical line first
- D Drain the air tanks
- A They have a higher rollover risk
- B They take more skill to back, couple, and uncouple
- C They are heavier and longer
- D All of the above
- A The drive wheels lock and the trailer pushes the tractor sideways
- B The trailer wheels lock briefly
- C You are driving slowly
- D The brakes are released gently
- A Be closed around the shank of the kingpin (not on the head)
- B Be loose
- C Be open
- D Be missing
Study tips for the Colorado Combination Vehicles exam
The Combination Vehicles portion of the Colorado CDL exam is graded out of the bank of questions the Colorado Department of Revenue Division of Motor Vehicles draws from each year. While the exact bank is not published, every question is sourced from the Combination Vehicles chapter of the Colorado 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 Colorado 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 Colorado Department of Revenue Division of Motor Vehicles 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 Colorado 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 Colorado 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 Colorado Department of Revenue Division of Motor Vehicles office.
Already comfortable with this endorsement? Drill another: CO General Knowledge · CO Air Brakes · CO Hazardous Materials · CO Passenger · CO School Bus · CO Tank Vehicle · CO Doubles / Triples
New to the CDL process in Colorado? Read How to apply for a CDL in Colorado for the document checklist and step-by-step timeline.