Texas Combination Vehicles CDL Practice Test
Below are 25 exam-style questions for the Texas Combination Vehicles CDL knowledge test, modeled on the FMCSA-aligned content used by the Texas Department of Public Safety. 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 Loss of traction
- B Driving off the road
- C The trailer wheels follow a tighter arc than the tractor wheels in a turn
- D Sliding sideways
- A Lose engine power
- B Spin out
- C Roll over before sliding
- D Stop suddenly
- A Failure to grease
- B Coupling with the trailer too high
- C All of the above
- D Backing too fast
- A No specific order is required
- B Release fifth wheel first, then connect lines
- C Pull tractor away first, then disconnect lines
- D Lower landing gear, disconnect lines, release fifth wheel, pull tractor away
- A The tractor parking brake fails
- B The drive wheels lose traction and the tractor begins to slide
- C The trailer is too heavy
- D The fifth wheel disengages
- A Is part of the tractor
- B Is used to convert a semitrailer into a full trailer for towing in combination
- C Is used only when triple-towing
- D Replaces the fifth wheel on the tractor
- A Steering becomes easier
- B Stopping distances are normal
- C No effect on safety
- D Stopping distances increase and the trailer can swing
- 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 The fifth wheel breaks
- B The tractor brakes lock up
- C The trailer brakes lock up
- D A wheel bearing fails
- A Locked and the safety latch in place after coupling
- B Removed before driving
- C Released and visible after coupling
- D Tied with rope
- A Driving too fast for conditions and/or too closely
- B Cargo movement
- C Worn out tires
- D Engine failure
- A Smoke from the cab
- B Pulling, sticking, or unusual feel as you apply the brakes
- C Engine knocking
- D Steering wander only
- A Honk the horn
- B Drain the air tanks
- C Lower the trailer landing gear and chock the trailer wheels
- D Disconnect the electrical line first
- A Set only the tractor parking brake
- B Leave the engine running with the brakes off
- C Use the trailer hand valve
- D Set both tractor and trailer parking brakes
- A Cargo placement
- B Loose lug nuts only
- C Engine oil leaks
- D Cuts, abrasions, and worn seals
- A Always halfway extended
- B Lowered to the ground while driving
- C Disconnected before driving
- D Fully raised before driving
- A The trailer following the same path as the tractor in a straight line
- B Lane positioning at intersections
- C The fuel mileage
- D Cargo placement
- A Back at full speed
- B GOAL — Get Out And Look — and walk around the trailer first
- C Have the dispatcher in the cab
- D Use only mirrors
- A Off-tracking — the trailer wheels follow a tighter arc than the tractor
- B No off-tracking
- C Brake fade
- D Wheel damage
- A You will notice immediately because trailer brakes will not work properly
- B Nothing will happen
- C The trailer brakes will be locked on
- D The horn will sound
- A Honk and accelerate
- B Shift in the middle of the track
- C Stop on the tracks if traffic ahead slows
- D Cross in a low gear without shifting
- A Back without using mirrors
- B Always back to the right
- C Back to the left whenever possible because you can see better
- D Back as fast as practical
- A Empty
- B Too high — it can damage the kingpin or skip over the fifth wheel
- C Properly chocked
- D Loaded
- A Round, blue, marked TRACTOR
- B Octagonal, red, marked TRAILER AIR SUPPLY
- C Square, white, marked CHARGE
- D Triangular, green, marked SERVICE
- A Whatever height it happens to be
- B Maximum legal height
- C A height where the tractor will lift the trailer slightly when backing under
- D A height that requires the tractor to drop down to fit
Study tips for the Texas Combination Vehicles exam
The Combination Vehicles portion of the Texas CDL exam is graded out of the bank of questions the Texas Department of Public Safety draws from each year. While the exact bank is not published, every question is sourced from the Combination Vehicles chapter of the Texas 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 Texas 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 Texas Department of Public Safety 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 Texas 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 Texas 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 Texas Department of Public Safety office.
Already comfortable with this endorsement? Drill another: TX General Knowledge · TX Air Brakes · TX Hazardous Materials · TX Passenger · TX School Bus · TX Tank Vehicle · TX Doubles / Triples
New to the CDL process in Texas? Read How to apply for a CDL in Texas for the document checklist and step-by-step timeline.