Colorado General Knowledge CDL Practice Test

This is a free 20-question practice test for the General Knowledge portion of the Colorado Commercial Driver's License knowledge exam. Questions are pulled from a pool of 97 drawn from the AAMVA CDL Manual, which is the source document the Colorado Division of Motor Vehicles 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 Colorado.

Question 1 of 20

When the engine is running in the cab inspection, you should check:

Oil pressure, ammeter/voltmeter, coolant temperature, engine oil temperature, and air pressure
Only the speedometer
Only the air-pressure gauge
Only the fuel gauge

Correct. After starting, watch the gauges to be sure all systems are operating normally before you drive.

Question 2 of 20

Which of these is a sign of tire failure?

Heavy thumping or vibration
A loud bang
The vehicle pulling to one side
All of the above

Correct. Vibration, a loud bang from a blowout, and pulling to one side are all classic signs of tire failure.

Question 3 of 20

What is the minimum tread depth required for the front (steering) tires of a commercial vehicle?

1/32 inch
2/32 inch
4/32 inch
6/32 inch

Correct. Steer-axle tires must have at least 4/32-inch tread depth in every major groove. Other tires require at least 2/32 inch.

Question 4 of 20

When approaching a downgrade, you should select:

A higher gear than you would for an upgrade
A lower gear before starting down, never after
Neutral, and let gravity slow you
Whatever gear you are in

Correct. Select your gear before the downgrade — modern transmissions can be hard or impossible to shift into a lower gear once you are descending and engine RPM has dropped.

Question 5 of 20

Stopping distance increases significantly when:

Brakes are wet
Tires are worn
You are heavily loaded
All of the above

Correct. Wet brakes, worn tires, heavy load, and slick pavement all extend stopping distance. Plan ahead and follow at greater intervals.

Question 6 of 20

How can you tell if you are driving in mountains?

You see deer
Your engine works harder on grades, both up and down
Roads are paved
It is colder

Correct. Mountain driving demands attention to grade-related challenges: gear selection on upgrades, speed control on downgrades, escape ramp awareness.

Question 7 of 20

Empty trucks:

Always stop in less distance than fully loaded ones
Require longer stopping distances than loaded ones because of lighter brake force per axle
Have the same stopping distance as loaded trucks
Cannot use the engine brake

Correct. An empty truck has lighter axle weight, so the brakes generate less friction relative to vehicle weight — the truck can take longer to stop than the same vehicle loaded.

Question 8 of 20

On a vehicle equipped with ABS, you should:

Pump the brakes during emergency stops
Apply the brakes the way you always have, with steady pressure
Use the parking brake instead
Never use the service brakes

Correct. With ABS, brake the way you always would. The system prevents wheel lockup automatically; pumping interrupts ABS function.

Question 9 of 20

When stopping at the scene of an accident, you should:

Move your vehicle into traffic to make room
Park well off the road, set out warning devices, and offer assistance
Leave the scene immediately
Drive around the accident

Correct. Park clear of the road, activate four-way flashers, set out warning triangles, and assist as you can without putting yourself in danger.

Question 10 of 20

Which of the following is true about driving at night?

Headlights illuminate further than you can stop within
You should drive faster to keep up with traffic
You should drive at a speed that lets you stop within the distance illuminated by your headlights
You can rely on oncoming headlights to help you see

Correct. Drive at a speed where your stopping distance does not exceed the distance you can see — typically 250 feet on low beams, 350-500 feet on high beams.

Question 11 of 20

What is the minimum amount of tread depth required on tires other than front (steering) tires?

1/32 inch
2/32 inch
4/32 inch
5/32 inch

Correct. Non-steer tires must have at least 2/32-inch tread depth in every major groove.

Question 12 of 20

What does it mean when a driver is "hydroplaning"?

The truck is overheating
The tires lose contact with the road and ride on a film of water
The brakes have failed
The driver is dehydrated

Correct. Hydroplaning means tires have lost contact with the pavement and are riding on standing water. Steering and braking become ineffective.

Question 13 of 20

When a vehicle ahead of you brakes hard, you should:

Brake harder
Apply the brakes immediately, even if you don't need to
Look for a way to steer around the vehicle if necessary, while preparing to brake
Honk to warn the driver behind you

Correct. Plan your escape: identify a clear lane or shoulder. If you can steer to safety, you save reaction time. If not, brake firmly without locking the wheels.

Question 14 of 20

When driving in heavy fog, you should:

Drive faster to get out of it
Use high-beam headlights
Pull off the road if visibility is too low to drive safely
Follow another vehicle's tail lights closely

Correct. If visibility is so poor that you cannot drive safely, pull completely off the road, turn on four-way flashers, and wait for conditions to improve.

Question 15 of 20

A "controlled braking" stop is:

Locking the wheels and steering
Applying the brakes hard, just short of wheel lockup
Pumping the brakes
Using the parking brake

Correct. Controlled braking applies the brakes as hard as you can without locking the wheels — used in emergency stops on non-ABS vehicles to retain steering.

Question 16 of 20

When you double your speed from 20 to 40 mph, the impact in a crash is:

Twice as great
Three times as great
Four times as great
The same

Correct. Crash energy is proportional to the square of speed. Doubling speed quadruples the energy of impact.

Question 17 of 20

You are about to drive a vehicle that you have not driven before. What should you do?

Get in and drive — every commercial vehicle handles the same
Inspect the vehicle to make sure it is safe and the cargo is properly secured
Drive briefly without cargo to learn the controls
Skip the inspection if the previous driver inspected it

Correct. Federal regulations require the driver to be satisfied that the vehicle is in safe operating condition before driving. The previous driver's inspection does not relieve you of that responsibility.

Question 18 of 20

On a 6-tire single vehicle, the maximum allowable air loss rate (engine off, brakes released) is:

1 psi per minute
2 psi per minute
3 psi per minute
4 psi per minute

Correct. For a single vehicle, no more than 2 psi per minute leakage with the engine off and brakes released. Combinations are limited to 3 psi/min.

Question 19 of 20

How often must drivers inspect their cargo and securing devices?

Within the first 50 miles, then every 150 miles or every 3 hours of driving (whichever comes first)
Only at the start of the trip
Only at fuel stops
Only when entering a new state

Correct. Federal rule: inspect within the first 50 miles, then every 150 miles or 3 hours of driving, whichever comes first, plus every change of duty status.

Question 20 of 20

Which of these is a major cause of crashes in heavy vehicles?

Driver fatigue
Heavy traffic
Following too closely
All of the above

Correct. Fatigue, heavy traffic, and following too closely are all leading factors in commercial vehicle crashes.

About the Colorado General Knowledge exam

Most state DMVs administer 50 General Knowledge questions and require 80% (40 correct) to pass. Questions are pulled from a much larger pool, so two applicants taking the test on the same day will see different mixes. The questions on this site are drawn from the AAMVA CDL Manual chapters that every state's exam is built from.

The Colorado Division of Motor Vehicles follows the federal CDL standards established by FMCSA. To earn the General Knowledge 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 General Knowledge question bank or browse all Colorado CDL practice tests.