South Dakota Combination Vehicles CDL Practice Test
Below are 25 exam-style questions for the South Dakota Combination Vehicles CDL knowledge test, modeled on the FMCSA-aligned content used by the South Dakota Driver Licensing Program. 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 Loose or missing fifth-wheel mounting bolts
- B All of the above
- C Misalignment between tractor and trailer
- D Cracks in the kingpin
- A It is fine if you are careful
- B It is illegal in some states
- C It is the standard procedure
- D It can damage the cab and the trailer (cab corner crush)
- A Roll over before sliding
- B Stop suddenly
- C Spin out
- D Lose engine power
- A Manual transmission shifters
- B Brake adjustment levers
- C Coupling devices for connecting tractor air lines to the trailer
- D Electrical connectors
- A Triangular, green, marked SERVICE
- B Octagonal, red, marked TRAILER AIR SUPPLY
- C Square, white, marked CHARGE
- D Round, blue, marked TRACTOR
- A Listen for a click
- B Look at the locking jaws only
- C Honk the horn
- D Tug the trailer with the trailer parking brakes set
- A No specific order is required
- B Pull tractor away first, then disconnect lines
- C Release fifth wheel first, then connect lines
- D Lower landing gear, disconnect lines, release fifth wheel, pull tractor away
- A Apply the trailer hand valve harder
- B Accelerate
- C Disconnect the air supply
- D Release the brakes to allow the trailer wheels to roll again, then steer
- A ABS prevents jackknife in all cases
- B Drive wheels never lock
- C Trailer wheels lock more often than drive wheels in panic stops
- D Brake balance is irrelevant
- A Drive away immediately
- B Pump the brakes 10 times
- C Drain the wet tank
- D Charge the trailer brakes by setting the trailer air supply control
- A By pushing in the red trailer-air-supply valve
- B By pulling out the red trailer-air-supply valve
- C By the trailer hand valve
- D By setting the red trailer-air-supply valve
- A No off-tracking
- B Off-tracking — the trailer wheels follow a tighter arc than the tractor
- C Brake fade
- D Wheel damage
- A Honk and accelerate
- B Shift in the middle of the track
- C Cross in a low gear without shifting
- D Stop on the tracks if traffic ahead slows
- A Fully raised before driving
- B Lowered to the ground while driving
- C Disconnected before driving
- D Always halfway extended
- A The tractor brakes lock up
- B The trailer brakes lock up
- C The fifth wheel breaks
- D A wheel bearing fails
- A A height where the tractor will lift the trailer slightly when backing under
- B Maximum legal height
- C A height that requires the tractor to drop down to fit
- D Whatever height it happens to be
- A Carries electrical signals
- B Drains the wet tank
- C Operates the parking brake only
- D Sends supply air to the trailer reservoirs and controls the trailer emergency brakes
- A Stop traffic by signaling left
- B Turn from the left lane
- C Use the shoulder
- D 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
- A All of the above
- B Coupling with the trailer too high
- C Backing too fast
- D Failure to grease
- A Loaded last
- B First (closest to the tractor)
- C Either position is fine
- D Last
- A The parking brake
- B The tractor service brakes only
- C Both tractor and trailer brakes simultaneously
- D The trailer service brakes only
- A Reduced visibility along the trailer
- B Off-tracking on right turns
- C Trailer sway in crosswinds
- D All of the above
- A They take more skill to back, couple, and uncouple
- B They are heavier and longer
- C They have a higher rollover risk
- D All of the above
- A Only at the destination
- B Before, during, and after coupling
- C Only at the start of the day
- D Every 3 hours
- A Connect any line first; order doesn't matter
- B Connect electrical first, then air
- C Connect air emergency line first, then service line, then electrical (or per company policy) — verify with brake check
- D Connect only air; electrical is optional
Study tips for the South Dakota Combination Vehicles exam
The Combination Vehicles portion of the South Dakota CDL exam is graded out of the bank of questions the South Dakota Driver Licensing Program draws from each year. While the exact bank is not published, every question is sourced from the Combination Vehicles chapter of the South Dakota 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 South Dakota 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 South Dakota Driver Licensing Program 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 South Dakota 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 South Dakota 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 South Dakota Driver Licensing Program office.
Already comfortable with this endorsement? Drill another: SD General Knowledge · SD Air Brakes · SD Hazardous Materials · SD Passenger · SD School Bus · SD Tank Vehicle · SD Doubles / Triples
New to the CDL process in South Dakota? Read How to apply for a CDL in South Dakota for the document checklist and step-by-step timeline.