CDL Combination Vehicles

First published: September 1, 2026Last verified: September 2, 2026Reviewed by the CertQuestUSA team

TL;DR

CDL Combination Vehicles: a 80-question practice bank for the real CDL Permit & Endorsement Exams standard, 3 full papers of 25 questions each with no repeats, every question citing the real regulation it comes from.

Where these questions come from

Every question in this bank cites a real source -- primarily FMCSA CDL Manual (95%) and 49 CFR (5%) of this exam's citations.

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3

full papers, no repeats

25

questions per paper

80

questions in the bank

What this exam covers

Combination Vehicle Air Brakes38%
Coupling and Uncoupling28%
Inspecting a Combination Vehicle13%
Combination Vehicle Overview and Dynamics23%

5 real sample questions

The CDL Manual says rollovers happen most often when a driver:

A. Turns too fast for the load and speed

B. Uses the parking brake at a stop light

C. Drains the air tanks before a trip

D. Checks mirrors too frequently while braking

Source: FMCSA CDL Manual §6.1

According to the CDL Manual, how much more likely is a fully loaded combination rig to roll over in a crash compared to an empty rig?

A. About twice as likely

B. About five times as likely

C. About ten times as likely

D. Loaded and empty rigs roll over at about the same rate

Source: FMCSA CDL Manual §6.1

Per the CDL Manual, what are the two most important things a driver can do to help prevent a combination vehicle rollover?

A. Keep the cargo as close to the ground as possible and drive slowly around turns

B. Run higher tire pressure and keep the fuel tanks full

C. Use the trailer hand valve on curves and accelerate through turns

D. Keep the fifth wheel greased and use cruise control on hills

Source: FMCSA CDL Manual §6.1

Why does the CDL Manual say cargo should be centered and spread out as much as possible on a combination vehicle?

A. Centered cargo reduces fuel consumption

B. If the load is to one side so it makes the trailer lean, a rollover is more likely

C. It is required only for hazardous materials loads

D. It keeps the fifth wheel plate from needing grease

Source: FMCSA CDL Manual §6.1

For the air and electric lines running to the trailer, what does the CDL Manual's inspection checklist call for?

A. Electrical cord firmly plugged in and secured; air lines properly connected to glad hands with no leaks and enough slack for turns; all lines free from damage

B. Only that the lines are the correct color

C. Only that the lines were replaced within the last 12 months

D. Only that the lines are longer than 10 feet

Source: FMCSA CDL Manual §6.4

Real-world data for this exam

Heavy and Tractor-Trailer Truck Drivers: real median wageMay 2025$58,640/yr Part of the real CDL Driver career pathExplore ›

Frequently asked questions

How many questions are on the CertQuestUSA CDL Combination Vehicles practice test?

80 questions total, split into 3 full papers of 25 each with no repeats across papers.

What topics does the CDL Combination Vehicles test cover?

4 domains, with the heaviest weight on Combination Vehicle Air Brakes (38%), Coupling and Uncoupling (28%), and Combination Vehicle Overview and Dynamics (23%).

Where do CertQuestUSA's CDL Combination Vehicles questions come from?

Primarily FMCSA CDL Manual (95%) and 49 CFR (5%) of this bank's citations -- computed directly from this exam's own question sources, not a generic description.

Is there a free diagnostic for CDL Combination Vehicles?

Yes -- 10 real questions across the exam's domains, no sign-up required, with a domain-by-domain breakdown at the end.

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