25 realistic Doubles and Triples practice questions for Tennessee CDL applicants. Required for: Drivers pulling more than one trailer. Official test: 20 questions, 16 correct to pass.
Question 1 of 25 · Vehicle Dynamics
What's the importance of "leverage" in doubles and triples?
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A.
Each trailer affects the others; the rear can amplify or reduce stability
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B.
It only affects fuel efficiency
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C.
It doesn't matter
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D.
It only affects loading
Correct answer: A.
Forces transfer between trailers; each one affects the stability of the combination.
Question 2 of 25 · Inspection
Why must drivers inspect the dolly before connecting?
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A.
To check for damage and proper operation
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B.
To verify the brakes work
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C.
To inspect the pintle hook
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D.
All of the above
Correct answer: D.
Dolly inspection includes structure, brakes, and pintle hook condition.
Question 3 of 25 · Speed Management
What's the safe speed for taking corners with doubles or triples?
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A.
Posted speed limit
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B.
Slower than single trailers
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C.
Higher than single trailers
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D.
No different from single trailers
Correct answer: B.
Take corners more slowly than single trailers due to greater rollover risk.
Question 4 of 25 · Following Distance
What's the best way to manage following distance with doubles?
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A.
Maintain extra distance compared to single trailers
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B.
Same as single trailers
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C.
Less distance
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D.
No following distance needed
Correct answer: A.
Doubles need more space because of longer stopping distances and reduced visibility.
Question 5 of 25 · Skids
What should you do if a trailer starts to skid?
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A.
Release the brakes to allow trailer wheels to roll
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B.
Apply more brake
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C.
Steer hard right
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D.
Accelerate
Correct answer: A.
Release brakes to let trailer wheels roll; steer to recover.
Question 6 of 25 · Adverse Conditions
What's the safest way to handle wind with doubles or triples?
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A.
Slow down and grip the wheel firmly
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B.
Speed up to clear the area
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C.
Use engine retarder
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D.
Lock the brakes
Correct answer: A.
Reduce speed and steer firmly. Wind affects long combinations more than singles.
Question 7 of 25 · Coupling
What's the proper procedure for coupling a second trailer?
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A.
Position the dolly under the second trailer, then back the lead trailer to the dolly
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B.
Drive the lead trailer over the dolly
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C.
Connect electrical first
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D.
Lower the landing gear
Correct answer: A.
Position the dolly first, then back the lead trailer to it for proper coupling.
Question 8 of 25 · Lane Changes
What's the major risk when changing lanes with doubles or triples?
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A.
The rear trailer may not follow exactly
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B.
Other vehicles may not see the long combination
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C.
The trailer may swing out
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D.
All of the above
Correct answer: D.
Visibility and rear-trailer tracking are both major lane-change risks.
Question 9 of 25 · Coupling
What's the role of safety chains on a converter dolly?
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A.
To support the dolly when uncoupled
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B.
To prevent the trailer from coming loose if the pintle hook fails
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C.
To improve traction
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D.
To act as a brake
Correct answer: B.
Safety chains keep the trailer attached if the pintle hook fails.
Question 10 of 25 · Cargo
Doubles and triples are most stable when:
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A.
All trailers are properly loaded
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B.
Trailers are empty
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C.
The lead trailer is empty
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D.
The rear trailer is heaviest
Correct answer: A.
Proper loading on every trailer is key to stability.
Question 11 of 25 · Operation
How should drivers approach intersections with doubles or triples?
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A.
Slow down and signal early to allow for the turn
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B.
Drive at full speed
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C.
Cut across lanes if needed
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D.
Use the engine retarder
Correct answer: A.
Slow down and signal well in advance to give time for the long combination.
Question 12 of 25 · Mountain Driving
What's the recommended speed when descending a steep grade with doubles?
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A.
Slow speed using lower gears and engine braking
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B.
Posted speed limit
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C.
Faster than single trailers
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D.
Use service brakes only
Correct answer: A.
Use lower gears and engine braking. Service brakes only intermittently.
Question 13 of 25 · Emergency Maneuvers
How should doubles drivers handle emergency braking?
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A.
Apply brakes firmly but smoothly
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B.
Use only the trailer hand valve
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C.
Pump the brakes
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D.
Use only the engine retarder
Correct answer: A.
Smooth, firm braking is best — let ABS work if equipped.
Question 14 of 25 · Operation
What's the safest way to merge into traffic with doubles?
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A.
Use turn signals early and merge gradually
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B.
Speed up to merge quickly
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C.
Force other drivers to yield
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D.
Drive on the shoulder
Correct answer: A.
Signal early and merge gradually so other drivers can adjust.
Question 15 of 25 · Speed Management
How should drivers approach a sharp curve with doubles?
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A.
Slow down well before the curve and steer smoothly
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B.
Maintain highway speed
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C.
Use engine retarder
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D.
Brake hard in the curve
Correct answer: A.
Slow down before the curve; smooth steering through the curve avoids rollover.
Question 16 of 25 · Backing
When backing doubles or triples, you should:
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A.
Avoid backing if possible
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B.
Use a helper as a spotter
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C.
Back slowly and carefully
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D.
All of the above
Correct answer: D.
Avoid backing combinations; use a spotter and go slowly when you must.
Question 17 of 25 · Vehicle Dynamics
How do you reduce off-tracking in doubles?
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A.
Make wider turns
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B.
Slow down
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C.
Use mirrors carefully
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D.
All of the above
Correct answer: D.
Wider turns, slower speed, and careful mirror use minimize off-tracking impact.
Question 18 of 25 · Vehicle Dynamics
What is "crack-the-whip"?
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A.
A driver discipline rule
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B.
When the rear trailer swings out due to sudden steering inputs
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C.
A type of weight distribution
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D.
A coupling procedure
Correct answer: B.
The rear trailer can swing far wider than the tractor, magnifying steering inputs.
Question 19 of 25 · Cargo
What's the impact of overloading a trailer in a doubles set?
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A.
Increased rollover risk
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B.
Poor handling
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C.
Brake problems
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D.
All of the above
Correct answer: D.
Overloading creates a chain of safety problems for the whole combination.
Question 20 of 25 · Coupling
What's a common mistake when coupling doubles?
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A.
Not properly aligning the dolly with the second trailer
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B.
Forgetting to connect air lines
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C.
Not testing the brakes
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D.
All of the above
Correct answer: D.
Alignment, air lines, and brake tests are common areas for mistakes.
Question 21 of 25 · Coupling
How do you prevent a trailer from rolling away when uncoupled?
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A.
Apply trailer brakes and chock the wheels
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B.
Use the parking brake on the tractor
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C.
Lower the landing gear quickly
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D.
Drive away quickly
Correct answer: A.
Set trailer brakes and chock wheels to prevent any roll while uncoupling.
Question 22 of 25 · Inspection
Why is it important to inspect each trailer separately?
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A.
Each trailer has its own systems and potential issues
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B.
It's easier to spot problems
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C.
It's required by law
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D.
All of the above
Correct answer: D.
Each trailer needs its own inspection of brakes, lights, and condition.
Question 23 of 25 · Inspection
What's the impact of poor maintenance on doubles or triples?
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A.
Increased risk of breakdowns and accidents
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B.
Poor fuel efficiency
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C.
Legal issues
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D.
All of the above
Correct answer: D.
Poor maintenance leads to safety, efficiency, and legal problems.
Question 24 of 25 · Coupling
How should you uncouple a converter dolly?
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A.
Lower the dolly support, disconnect, and pull the tractor and first trailer away
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B.
Disconnect and drive away
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C.
Use the trailer parking brake
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D.
Cut the air lines
Correct answer: A.
Lower support, disconnect lines and pin, then pull the lead unit away.
Question 25 of 25 · Cargo
What's the consequence of bad weight distribution in doubles?
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A.
Increased rollover risk
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B.
Poor handling
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C.
Tire wear
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D.
All of the above
Correct answer: D.
Bad distribution increases rollover, handling problems, and tire wear.
About the Doubles and Triples Test
The Doubles and Triples test covers pulling double and triple trailers, coupling and uncoupling, inspecting doubles and triples, antilock brake systems, and safe driving with multiple trailers. Doubles and triples are more likely to roll over than single trailers and are extremely sensitive to steering inputs at the rear trailer.
The Tennessee Department of Safety — Driver Services administers this knowledge test as part of its commercial driver license program. To earn the Doubles/Triples (T) on your Tennessee CDL, you need to score at least 16 out of 20 on the official version.
Topics covered on this practice test
- Coupling: 5 questions
- Vehicle Dynamics: 3 questions
- Inspection: 3 questions
- Cargo: 3 questions
- Speed Management: 2 questions
- Operation: 2 questions
- Following Distance: 1 question
- Skids: 1 question
- Adverse Conditions: 1 question
- Lane Changes: 1 question
- Mountain Driving: 1 question
- Emergency Maneuvers: 1 question
- Backing: 1 question
How to use this practice test
- Read each question carefully. CDL questions are written precisely — small wording differences matter.
- Click "Show Answers & Explanations" only after answering every question. Don't peek mid-test.
- Read the explanation for every question, even ones you got right. The reasoning is more important than the answer.
- Repeat the test until you score 100%. The questions are deterministic per state, so you can track your improvement over multiple sessions.
- Move on to the other endorsement tests for Tennessee until you're ready for the official exam.
Tips specific to the Doubles and Triples test
Doubles and Triples questions emphasize the "crack-the-whip" effect, converter dolly inspection and use, pintle hooks, safety chains, the heaviest-trailer-first loading rule, and the higher rollover risk of multi-trailer combinations. Many states prohibit triples; check local rules.