Idaho Doubles / Triples CDL Practice Test
Below are 25 exam-style questions for the Idaho Doubles / Triples CDL knowledge test, modeled on the FMCSA-aligned content used by the Idaho Transportation Department 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 Potential rollover at curves
- B Crosswind effects on the rear trailer
- C All of the above
- D Lane changes that swing the rear
- A Reduced visibility around the second trailer
- B Crosswind sensitivity
- C Increased rollover risk in curves
- D All of the above
- A It can sway and lift more easily; drive carefully
- B It is harder to roll over
- C Better fuel mileage
- D No change in handling
- A Any lane
- B The shoulder
- C The right lane on multilane highways when possible
- D The left lane
- A Skip the parking brake
- B Allow the dolly to roll
- C Disconnect at high speed
- D Set the parking brake or chock the wheels before disconnecting
- A Accelerate
- B Brake hard
- C Reduce speed gradually and avoid sudden steering inputs
- D Steer sharply
- A All of the above
- B Cargo placement
- C Wind, especially crosswinds and from passing trucks
- D Lane changes
- A Mechanical brakes only
- B No air-brake system
- C Air lines from tractor to first trailer to dolly to second trailer
- D Air lines only on the tractor
- A A combination with a second trailer that has a kingpin attached to the first trailer
- B A type of bus
- C A train carrying buses
- D A type of car carrier
- A Disable the brakes
- B Park it on level ground with the parking brake set or wheels chocked
- C Connect it to a random trailer
- D Leave it on a slope
- A A tractor only
- B A converter dolly
- C A trailer for transporting animals
- D A short trailer commonly used in doubles and triples
- A Reduce speed gradually and avoid sudden steering inputs
- B Brake hard
- C Accelerate
- D Steer sharply to correct
- A In some states; restrictions vary
- B On all U.S. highways
- C In Canada only
- D Only on Interstate 80
- A Allow the dolly to roll freely
- B Verify the dolly's air tank has air pressure and lock the dolly's parking brake before backing under the second trailer
- C Skip the air check
- D Couple without verifying
- A Air lines, electrical lines, and connection points
- B Fuel tanks
- C Drivers
- D Engines
- A Move cargo within the trailer
- B Test the brakes
- C Replace the fifth wheel on the tractor
- D Connect a semitrailer to another trailer to form a combination
- A Are required only on triples
- B Carry electrical signals
- C Are decorative
- D Provide a backup connection in case the primary coupling fails
- A Includes a pintle hook on the front and a fifth wheel on the back
- B Is a single hook
- C Is electrical only
- D Is the same as a tractor fifth wheel
- A Change at high speed
- B Change quickly without signaling
- C Change in heavy traffic
- D Signal early and change smoothly to minimize swing
- A Drive as if it were a single trailer
- B Use the trailer hand valve as a parking brake
- C Skip the pre-trip
- D Be aware of the increased complexity of the equipment and operate accordingly
- A Increase speed
- B Maintain speed
- C Brake within the curve
- D Slow down before the curve to reduce rollover risk and trailer swing
- A Ignore the damage
- B Replace before operating
- C Use the spare
- D Continue with damaged tires
- A State and federal route restrictions
- B Coupling and uncoupling procedures
- C All of the above
- D How to inspect each connection point
- A No effect on safety
- B More opportunities for tire failure and more inspection points
- C Fewer inspection points
- D Better handling
- A Verify the fifth wheel locks around the kingpin and test by tugging gently
- B Skip the lock verification
- C Trust visual inspection only
- D Couple at high speed
Study tips for the Idaho Doubles / Triples exam
The Doubles / Triples portion of the Idaho CDL exam is graded out of the bank of questions the Idaho Transportation Department Division of Motor Vehicles draws from each year. While the exact bank is not published, every question is sourced from the Doubles / Triples chapter of the Idaho 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 Idaho 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 Doubles / Triples.
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 Idaho Transportation Department 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 Doubles / Triples 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 Idaho General Knowledge practice test before scheduling the real exam.
Next steps
Missed more than four questions? Re-read the Doubles / Triples study guide and the matching chapter in the official Idaho 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 Idaho Transportation Department Division of Motor Vehicles office.
Already comfortable with this endorsement? Drill another: ID General Knowledge · ID Air Brakes · ID Combination Vehicles · ID Hazardous Materials · ID Passenger · ID School Bus · ID Tank Vehicle
New to the CDL process in Idaho? Read How to apply for a CDL in Idaho for the document checklist and step-by-step timeline.