Minnesota Doubles/Triples CDL Practice Test

This is a free 20-question practice test for the Doubles/Triples portion of the Minnesota Commercial Driver's License knowledge exam. Questions are pulled from a pool of 50 drawn from the AAMVA CDL Manual, which is the source document the Minnesota Driver and Vehicle Services uses to write its actual exam.

How it works: Click an answer. The correct choice highlights in green, and you'll see a short explanation. Aim for 85% or better before you sit for the real test in Minnesota.

Question 1 of 20

When parking a doubles rig:

Park where you can pull straight out — back-out is impractical
Back into any spot
Park in the entrance
Block the lane

Correct. Choose pull-through parking. Multi-trailer rigs cannot back any meaningful distance safely.

Question 2 of 20

A converter-dolly fifth wheel must be:

Properly lubricated and have correctly functioning locking jaws
Painted
Wide
Empty

Correct. Inspect for proper lubrication, no excessive wear, and confirm the locking jaws operate correctly. The dolly fifth wheel is just as critical as the tractor's.

Question 3 of 20

When you encounter a breakaway in your doubles (a trailer separates):

Maintain control of the tractor and lead trailer, brake gently to a controlled stop, set warning devices, and contact dispatch
Brake hard
Speed up
Swerve sharply

Correct. Maintain control of what remains, brake gently and progressively, secure the area with warning devices, contact dispatch.

Question 4 of 20

Safety chains on a converter dolly are required to:

Prevent the dolly from disconnecting if the pintle hook fails
Decorate the rig
Bind cargo
Add weight

Correct. Safety chains catch the dolly if the pintle hook releases or fails — preventing the trailer behind from breaking loose.

Question 5 of 20

An empty rear trailer on a multi-trailer rig:

Is more likely to roll over in evasive steering than a loaded one
Is always stable
Cannot roll over
Has no effect

Correct. Lighter trailer = more vulnerable to crack-the-whip and crosswinds. Empty rear trailers in multi-trailer rigs roll easily.

Question 6 of 20

When inspecting a converter dolly, the pintle hook must:

Lock fully closed around the lunette eye
Be loose
Be cracked
Be replaced quarterly

Correct. The pintle hook must close fully around the lunette eye, with no excessive wear or cracks. Add safety chains as backup.

Question 7 of 20

In a multi-trailer combination, the most violent movement during evasive maneuvers happens at:

The tractor
The first trailer
The last trailer
The cab

Correct. Rearward amplification (crack-the-whip effect) is greatest at the rear-most trailer. The last trailer in a triple can be thrown sideways with much greater force than the tractor.

Question 8 of 20

Doubles and triples should not be driven:

On slippery roads at normal speed
On dry, straight highways
In any conditions
Only at low speed

Correct. On slippery roads, multi-trailer rigs lose stability quickly. Reduce speed substantially and increase following distance.

Question 9 of 20

You discover a flat tire on the rear trailer of a triple. You should:

Continue driving
Pull off safely, set warning devices, and have the tire repaired or replaced before continuing
Drive only at night
Drive faster to balance

Correct. A flat tire affects rig stability and brake load. Pull off safely, use warning devices, and address the tire.

Question 10 of 20

When backing a doubles or triples combination:

Avoid it whenever possible — multi-trailer rigs cannot be backed any meaningful distance safely
Back at full speed
Back without a helper
Use only the trailer brake

Correct. Doubles and triples cannot be backed safely beyond a few feet — joints flex unpredictably. Plan your route and parking to avoid backing.

Question 11 of 20

Driving doubles or triples on the highway:

Requires gentler steering, longer following distance, and earlier braking
Allows the same maneuvers as a single trailer
Allows higher cornering speeds
Has no special concerns

Correct. Multi-trailer rigs are more sensitive to abrupt steering, take longer to brake, and amplify any movement to the rear. Be gentle and plan ahead.

Question 12 of 20

When testing the brakes on a doubles rig:

Do all the standard checks plus verify air pressure builds at the rear trailer and that brakes apply at all wheels
Only test the tractor
Only test the lead trailer
Skip the test

Correct. Test the entire rig: build-up time, leakage, low-pressure warning, parking brake, and confirm rear-trailer brake function.

Question 13 of 20

On a steep downgrade with doubles, you should:

Select a lower gear before starting down and use intermittent firm braking
Coast in neutral
Use only trailer brake
Stay in high gear

Correct. Same rule as any combination vehicle, but plan extra margin: doubles take longer to stop and the rear trailer may push.

Question 14 of 20

Coupling order for a set of doubles starts with:

Coupling the lead (front) trailer to the tractor first, charging air, then attaching the converter dolly to the rear of the lead trailer, then attaching the second trailer
Coupling the rear trailer first
Coupling the dolly first
It does not matter

Correct. Standard order: tractor + lead trailer first, charge air, then attach converter dolly behind lead trailer, then second trailer to dolly.

Question 15 of 20

When you uncouple a converter dolly, you should:

Disconnect air and electrical, secure or remove safety chains, then release the pintle hook
Just yank it off
Drive forward fast
Use only the trailer brake

Correct. Park level, disconnect air and electric, lower trailer landing gear if applicable, remove safety chains, then release the pintle hook to free the dolly.

Question 16 of 20

On a triple, the air pressure to the rearmost trailer:

Is the same as the lead
Is delayed by line length, so braking response at the rear trailer lags noticeably
Is faster
Does not exist

Correct. Greater line length = greater brake-lag at the rear. Plan braking earlier than you would for a single trailer.

Question 17 of 20

A "set of doubles" typically refers to:

A tractor pulling two trailers
One tractor with one long trailer
Two tractors and a trailer
Two tractors and two trailers

Correct. A "set of doubles" is one tractor pulling two trailers (typically two pups, each about 28 feet long, in LTL operations).

Question 18 of 20

When adjusting the order of trailers in a multi-trailer rig:

Place the heaviest immediately behind the tractor and progressively lighter to the rear
Place the heaviest at the rear
Order does not matter
Order is alphabetical

Correct. Heaviest first, lightest last. This minimizes rearward amplification and rollover risk in the rear trailers.

Question 19 of 20

A doubles rig is more likely to roll over than a single because:

The center of gravity is higher
The crack-the-whip effect amplifies steering input at the rear, where rollover threshold is lower
It is heavier
It is shorter

Correct. Multi-trailer rollover comes from rearward amplification — even modest steering input at the tractor becomes a violent swing at the rear trailer.

Question 20 of 20

Before connecting a converter dolly, you should:

Inspect tires, brakes, fifth-wheel jaws, and overall condition
Skip inspection
Only check the tires
Only check the lights

Correct. Pre-trip the dolly: tires, brake adjustment, fifth-wheel jaws (open and clean), pintle hook, electrical receptacle, lights.

About the Minnesota Doubles/Triples exam

Most states administer 20 Doubles/Triples questions and require 80% to pass. The exam emphasizes coupling and uncoupling the converter dolly, rearward amplification (the "crack-the-whip" effect), and the unique inspection and handling demands of multi-trailer rigs.

The Minnesota Driver and Vehicle Services follows the federal CDL standards established by FMCSA. To earn the Doubles/Triples credential, you must answer at least 80% of the questions correctly. Many candidates score lower the first time because the test pulls from a large pool — refreshing this page will give you a different mix of questions, drawn from the same authoritative source.

Want more practice? Try the full Doubles/Triples question bank or browse all Minnesota CDL practice tests.