Louisiana Combination Vehicles CDL Practice Test
Below are 25 exam-style questions for the Louisiana Combination Vehicles CDL knowledge test, modeled on the FMCSA-aligned content used by the Louisiana Office 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 Be closed around the shank of the kingpin (not on the head)
- B Be open
- C Be loose
- D Be missing
- A A height that requires the tractor to drop down to fit
- B A height where the tractor will lift the trailer slightly when backing under
- C Whatever height it happens to be
- D Maximum legal height
- A Only at the destination
- B Every 3 hours
- C Only at the start of the day
- D Before, during, and after coupling
- A May actually take longer to stop because brakes are designed for the loaded weight
- B Stops faster than when loaded
- C Stops only with parking brake
- D Stops in the same distance
- A The trailer wheels follow a tighter arc than the tractor wheels in a turn
- B Loss of traction
- C Sliding sideways
- D Driving off the road
- A No effect on safety
- B Stopping distances increase and the trailer can swing
- C Steering becomes easier
- D Stopping distances are normal
- A Be removed
- B Be locked at half-height
- C Be in the stowed (high) position when traveling
- D Be in the low position when traveling
- A Round, blue, marked TRACTOR
- B Octagonal, red, marked TRAILER AIR SUPPLY
- C Square, white, marked CHARGE
- D Triangular, green, marked SERVICE
- A Tug the trailer with the trailer parking brakes set
- B Honk the horn
- C Listen for a click
- D Look at the locking jaws only
- A Hand valves
- B Hydraulic brakes
- C A separate compressor
- D Sensors at each wheel that release brake pressure when wheel lockup is detected
- A Worn out tires
- B Cargo movement
- C Engine failure
- D Driving too fast for conditions and/or too closely
- A Coupling devices for connecting tractor air lines to the trailer
- B Brake adjustment levers
- C Manual transmission shifters
- D Electrical connectors
- A GOAL — Get Out And Look — and walk around the trailer first
- B Back at full speed
- C Have the dispatcher in the cab
- D Use only mirrors
- A The trailer is too heavy
- B The tractor parking brake fails
- C The drive wheels lose traction and the tractor begins to slide
- D The fifth wheel disengages
- A Back to the left whenever possible because you can see better
- B Back without using mirrors
- C Always back to the right
- D Back as fast as practical
- A A vehicle length
- B Two car lengths
- C No specific rule
- D One second per 10 feet of vehicle length below 40 mph, plus one extra second above 40 mph
- A Disconnected before driving
- B Always halfway extended
- C Fully raised before driving
- D Lowered to the ground while driving
- A Removed before driving
- B Released and visible after coupling
- C Locked and the safety latch in place after coupling
- D Tied with rope
- A Only need attention every 5 years
- B Make the truck quieter
- C Are normal until the lining is gone
- D Should be replaced when worn beyond manufacturer specs
- A Sends air pressure to apply trailer service brakes
- B Carries electrical power
- C Drains the trailer reservoir
- D Sends supply air to the trailer reservoirs
- A Lower landing gear, disconnect lines, release fifth wheel, pull tractor away
- B Release fifth wheel first, then connect lines
- C Pull tractor away first, then disconnect lines
- D No specific order is required
- A Connect air emergency line first, then service line, then electrical (or per company policy) — verify with brake check
- B Connect any line first; order doesn't matter
- C Connect electrical first, then air
- D Connect only air; electrical is optional
- A Release the brakes to allow the trailer wheels to roll again, then steer
- B Apply the trailer hand valve harder
- C Disconnect the air supply
- D Accelerate
- A Move the tractor far away immediately without checking
- B Connect the lines back to the tractor
- C Disable the trailer parking brake
- D Check that the trailer is stable on its landing gear
- A Properly chocked
- B Loaded
- C Empty
- D Too high — it can damage the kingpin or skip over the fifth wheel
Study tips for the Louisiana Combination Vehicles exam
The Combination Vehicles portion of the Louisiana CDL exam is graded out of the bank of questions the Louisiana Office 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 Louisiana 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 Louisiana 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 Louisiana Office 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 Louisiana 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 Louisiana 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 Louisiana Office of Motor Vehicles office.
Already comfortable with this endorsement? Drill another: LA General Knowledge · LA Air Brakes · LA Hazardous Materials · LA Passenger · LA School Bus · LA Tank Vehicle · LA Doubles / Triples
New to the CDL process in Louisiana? Read How to apply for a CDL in Louisiana for the document checklist and step-by-step timeline.