Ohio Combination Vehicles CDL Practice Test
Below are 25 exam-style questions for the Ohio Combination Vehicles CDL knowledge test, modeled on the FMCSA-aligned content used by the Ohio Bureau 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 Driving off the road
- B The trailer wheels follow a tighter arc than the tractor wheels in a turn
- C Loss of traction
- D Sliding sideways
- A Spin out
- B Roll over before sliding
- C Lose engine power
- D Stop suddenly
- A Back to the left whenever possible because you can see better
- B Always back to the right
- C Back without using mirrors
- D Back as fast as practical
- A One second per 10 feet of vehicle length below 40 mph, plus one extra second above 40 mph
- B Two car lengths
- C A vehicle length
- D No specific rule
- A The tractor brakes lock up
- B The trailer brakes lock up
- C The fifth wheel breaks
- D A wheel bearing fails
- A A separate compressor
- B Hand valves
- C Sensors at each wheel that release brake pressure when wheel lockup is detected
- D Hydraulic brakes
- A Both for parking and to prevent jackknife
- B Apply trailer brakes momentarily
- C Test the trailer brakes
- D Hold the vehicle when parking
- A The trailer to come uncoupled
- B Engine damage
- C Tire wear only
- D Rust on the cab
- A Pump the brakes 10 times
- B Drain the wet tank
- C Charge the trailer brakes by setting the trailer air supply control
- D Drive away immediately
- A Loose or missing fifth-wheel mounting bolts
- B Misalignment between tractor and trailer
- C Cracks in the kingpin
- D All of the above
- 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 Show up only at high speed
- B Are caused by low fuel
- C Need a mechanic to find
- D Can be detected during pre-trip inspection by visual and pressure checks
- A Use the shoulder
- B Stop traffic by signaling left
- C Turn from the left lane
- 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 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 The tractor parking brake fails
- B The trailer is too heavy
- C The drive wheels lose traction and the tractor begins to slide
- D The fifth wheel disengages
- A By setting the red trailer-air-supply valve
- B By pushing in the red trailer-air-supply valve
- C By pulling out the red trailer-air-supply valve
- D By the trailer hand valve
- A Off-tracking — the trailer wheels follow a tighter arc than the tractor
- B Brake fade
- C Wheel damage
- D No off-tracking
- A Listen for a click
- B Honk the horn
- C Tug the trailer with the trailer parking brakes set
- D Look at the locking jaws only
- A Driver fatigue
- B Cargo placement
- C Air leakage in the supply line, low pressure, or a brake-balance issue
- D Engine wear
- A Empty
- B Too high — it can damage the kingpin or skip over the fifth wheel
- C Loaded
- D Properly chocked
- A Be locked at half-height
- B Be in the low position when traveling
- C Be in the stowed (high) position when traveling
- D Be removed
- A Make the truck quieter
- B Should be replaced when worn beyond manufacturer specs
- C Are normal until the lining is gone
- D Only need attention every 5 years
- A Always halfway extended
- B Fully raised before driving
- C Disconnected before driving
- D Lowered to the ground while driving
- A Leave the engine running with the brakes off
- B Set both tractor and trailer parking brakes
- C Set only the tractor parking brake
- D Use the trailer hand valve
- A Fuel
- B Hydraulic fluid
- C Air for the brakes
- D Electrical power for trailer lights and ABS
Study tips for the Ohio Combination Vehicles exam
The Combination Vehicles portion of the Ohio CDL exam is graded out of the bank of questions the Ohio Bureau 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 Ohio 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 Ohio 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 Ohio Bureau 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 Ohio 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 Ohio 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 Ohio Bureau of Motor Vehicles office.
Already comfortable with this endorsement? Drill another: OH General Knowledge · OH Air Brakes · OH Hazardous Materials · OH Passenger · OH School Bus · OH Tank Vehicle · OH Doubles / Triples
New to the CDL process in Ohio? Read How to apply for a CDL in Ohio for the document checklist and step-by-step timeline.