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CO · T Endorsement

Colorado Doubles / Triples CDL Practice Test

Below are 25 exam-style questions for the Colorado Doubles / Triples CDL knowledge test, modeled on the FMCSA-aligned content used by the Colorado Department of Revenue 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.

Heads up: this is a study tool, not a graded exam. Cover the answer with your hand or a sheet of paper for an honest practice run, then re-read the explanations for any questions you missed. Aim for 22 out of 25 or better, three times in a row, before scheduling the real exam.
Question 1 of 25
When you need to make a lane change in heavy traffic with doubles:
  • A Cut between cars
  • B Change quickly to fit in
  • C Plan the change well in advance, signal early, and change when there is ample space
  • D Skip the signal
Correct answer: C
Planning and patience prevent collisions.
Question 2 of 25
A doubles/triples driver should test the trailer brakes:
  • A Before pulling away from the coupling site
  • B Never; the dispatcher tests them
  • C Only at the destination
  • D Once a year
Correct answer: A
Test trailer brakes immediately after coupling and before any movement.
Question 3 of 25
When the trailers are properly coupled:
  • A Some lines may be optional
  • B All air lines and electrical lines should be connected and tested
  • C Skip the testing
  • D Test only one line
Correct answer: B
Every connection must be tested before pulling away.
Question 4 of 25
A doubles driver should be aware of:
  • A No specific length
  • B Tractor length only
  • C Trailer length only
  • D Total combination length when turning, parking, and changing lanes
Correct answer: D
Total length affects every maneuver.
Question 5 of 25
A doubles/triples driver should know that:
  • A T endorsement allows triples everywhere
  • B Federal and state rules vary; T endorsement does not override route restrictions
  • C There are no restrictions
  • D Restrictions apply only to hazmat
Correct answer: B
Endorsement allows you to pull; route restrictions still apply.
Question 6 of 25
When you need to back a doubles combination:
  • A Use only mirrors
  • B Back at full speed
  • C Avoid it; if necessary, uncouple to a single trailer first
  • D Have a passenger guide you
Correct answer: C
Backing doubles is extremely difficult; uncouple if possible.
Question 7 of 25
In a doubles combination, the second (rear) trailer:
  • A Is more likely to roll than the first
  • B Is less likely to roll
  • C Cannot roll
  • D Has the same rollover risk
Correct answer: A
Rear trailer in a doubles is the most rollover-prone unit.
Question 8 of 25
When the air-supply line to the second trailer disconnects accidentally:
  • A The second trailer's emergency brakes apply automatically
  • B The tractor brakes apply
  • C The first trailer accelerates
  • D Nothing happens
Correct answer: A
Loss of supply pressure triggers emergency brakes — the failsafe.
Question 9 of 25
When uncoupling a converter dolly:
  • A Set the parking brake or chock the wheels before disconnecting
  • B Disconnect at high speed
  • C Skip the parking brake
  • D Allow the dolly to roll
Correct answer: A
Brake setting prevents dolly movement during disconnect.
Question 10 of 25
A "coupling device" on a converter dolly:
  • A Is a single hook
  • B Includes a pintle hook on the front and a fifth wheel on the back
  • C Is the same as a tractor fifth wheel
  • D Is electrical only
Correct answer: B
Converter dollies have both ends: pintle hook to attach to the lead trailer, fifth wheel for the trailing trailer's kingpin.
Question 11 of 25
A doubles combination has more tires, which means:
  • A More opportunities for tire failure and more inspection points
  • B Fewer inspection points
  • C No effect on safety
  • D Better handling
Correct answer: A
More tires = more inspection time and more potential failures.
Question 12 of 25
When the driver brakes a doubles combination:
  • A All trailers should brake together if the system is functioning correctly
  • B Only the first trailer brakes
  • C Brakes are uneven
  • D Only the rear trailer brakes
Correct answer: A
Air-brake system applies all wheels simultaneously when functioning correctly.
Question 13 of 25
When approaching a curve in a doubles combination:
  • A Brake within the curve
  • B Maintain speed
  • C Increase speed
  • D Slow down before the curve to reduce rollover risk and trailer swing
Correct answer: D
Speed reduction before the curve prevents rollover.
Question 14 of 25
The trailer hand valve on a doubles/triples combination operates:
  • A Tractor and trailer brakes
  • B Only the first trailer brakes
  • C Only the rear trailer brakes
  • D All trailer service brakes simultaneously
Correct answer: D
Hand valve applies all trailer service brakes; do not use as a parking brake.
Question 15 of 25
When the rear trailer's tires are improperly inflated:
  • A No effect
  • B Better fuel mileage
  • C Handling and braking are affected
  • D Better handling
Correct answer: C
Tire pressure affects every aspect of trailer handling and braking.
Question 16 of 25
Doubles and triples are sensitive to:
  • A Cargo placement
  • B Lane changes
  • C All of the above
  • D Wind, especially crosswinds and from passing trucks
Correct answer: C
All three are handling considerations.
Question 17 of 25
Safety chains on a doubles combination:
  • A Are required only on triples
  • B Provide a backup connection in case the primary coupling fails
  • C Carry electrical signals
  • D Are decorative
Correct answer: B
Safety chains hold the trailer if the primary coupling fails.
Question 18 of 25
When inspecting the trailer floor:
  • A Skip the floor inspection
  • B Allow damage
  • C Look for damage that could affect cargo securement or trailer integrity
  • D Inspect once a year
Correct answer: C
Floor damage can compromise the trailer and the load.
Question 19 of 25
When pulling doubles or triples, the heaviest trailer should be:
  • A First (closest to the tractor)
  • B It does not matter
  • C Last (furthest from the tractor)
  • D In the middle
Correct answer: A
Heavier trailer first reduces sway and improves handling.
Question 20 of 25
When the converter dolly's air tank is empty:
  • A Charge it before coupling and verify pressure
  • B Skip the charge
  • C Couple without checking
  • D Use the trailer hand valve to charge
Correct answer: A
Charging the dolly's tank ensures the trailer brakes will release properly.
Question 21 of 25
When the rear trailer of a doubles combination begins to sway:
  • A Brake hard
  • B Reduce speed gradually and avoid sudden steering inputs
  • C Accelerate
  • D Steer sharply to correct
Correct answer: B
Smooth reduction in speed allows the trailer to settle.
Question 22 of 25
A doubles combination requires:
  • A Air lines only on the tractor
  • B No air-brake system
  • C Mechanical brakes only
  • D Air lines from tractor to first trailer to dolly to second trailer
Correct answer: D
Air system extends through the entire combination via glad hands at each connection.
Question 23 of 25
When backing doubles, you should:
  • A Back at full speed
  • B Avoid backing whenever possible; use a spotter when needed
  • C Use only mirrors
  • D Skip the spotter
Correct answer: B
Backing doubles is high-risk and rarely necessary; avoid when possible.
Question 24 of 25
When checking the dolly's pintle hook:
  • A Allow loose engagement
  • B Verify it is properly engaged and safety chains are attached
  • C Skip the safety chains
  • D Allow chains to drag
Correct answer: B
Pintle hooks must be locked and safety chains attached.
Question 25 of 25
In a panic stop with doubles, the:
  • A Brakes work better
  • B Speed is reduced faster
  • C Tractor cannot jackknife
  • D Rear trailer can swing out and cause loss of control
Correct answer: D
Trailer swing and rollover are major risks during panic stops.

Study tips for the Colorado Doubles / Triples exam

The Doubles / Triples portion of the Colorado CDL exam is graded out of the bank of questions the Colorado Department of Revenue 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 Colorado 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 Colorado 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 Colorado Department of Revenue 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 Colorado 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 Colorado 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 Colorado Department of Revenue Division of Motor Vehicles office.

Already comfortable with this endorsement? Drill another: CO General Knowledge · CO Air Brakes · CO Combination Vehicles · CO Hazardous Materials · CO Passenger · CO School Bus · CO Tank Vehicle

New to the CDL process in Colorado? Read How to apply for a CDL in Colorado for the document checklist and step-by-step timeline.