New Mexico General Knowledge CDL Practice Test

This is a free 20-question practice test for the General Knowledge portion of the New Mexico 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 New Mexico Motor Vehicle Division 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 New Mexico.

Question 1 of 20

A driver-side skid can cause a tractor-trailer to:

Drift gently
Jackknife
Improve steering
Over-correct only the trailer

Correct. When the drive wheels lose traction and the trailer continues forward, the tractor pivots and the rig jackknifes.

Question 2 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 3 of 20

A driver should look down the road how far when driving at highway speeds?

One block
One-quarter mile (about 12-15 seconds ahead)
Just past the hood
To the horizon only

Correct. Look 12-15 seconds ahead — about a quarter mile at highway speeds. This gives time to identify and react to hazards.

Question 4 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 5 of 20

Convex (curved or "fish-eye") mirrors:

Show objects larger than they appear
Show a wider area but make objects look smaller and farther away than they actually are
Are not legal on commercial vehicles
Cannot be used at night

Correct. Convex mirrors widen the field of view but distort distance — objects appear smaller and farther away than they are.

Question 6 of 20

Which is the proper position for your hands on the steering wheel?

Both hands on the same side
One hand on top, one in your lap
Both hands firmly on opposite sides of the wheel (e.g., 9 and 3)
One hand on the wheel, one on the gear shift

Correct. Both hands should be on opposite sides of the wheel — typically the 9 o'clock and 3 o'clock positions — for steering control.

Question 7 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 8 of 20

When approaching a railroad crossing, drivers of buses, school buses, and placarded hazmat vehicles must:

Speed up to clear quickly
Stop between 15 and 50 feet from the nearest rail and listen
Cross only if a train is in sight
Sound the horn

Correct. Buses, school buses, and placarded hazmat vehicles must stop at every crossing, 15 to 50 feet from the nearest rail. Look and listen, then proceed when safe.

Question 9 of 20

Federal regulations require a tie-down for every cargo, with a minimum of:

One tie-down for any cargo
One tie-down for items less than 5 feet long, two for items 5+ feet
At least one tie-down for each 10 feet of cargo, with minimums depending on length and weight
Tie-downs are not required for closed trailers

Correct. The general rule: at least one tie-down per 10 feet of article, plus a minimum based on length and weight (commonly two minimum for items over 5 feet or 1,100 lbs).

Question 10 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 11 of 20

A vehicle's "no zone":

Refers to the lane next to the cab
Includes the front, sides, and rear blind spots where other vehicles disappear from view
Is the area in front of the truck only
Does not exist for cars

Correct. The "no zone" is the set of blind spots around a truck — front, both sides (especially right), and rear — where other vehicles cannot be seen.

Question 12 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 13 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 14 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 15 of 20

You are driving on a steep downgrade and your brakes have failed. The best escape is to:

Pump the brakes furiously
Use a runaway escape ramp
Try to bail out of the cab
Sound the horn and continue

Correct. If a runaway escape ramp is available, use it. Modern arrester beds use loose gravel or sand to slow the vehicle without injury to the driver.

Question 16 of 20

Which of these statements about backing a heavy vehicle is true?

Backing is always safe if you go slow
Whenever possible, use a helper outside the vehicle to guide you
Always back from the right side because you can see better
Backing is the same as backing a car

Correct. Backing is always risky for heavy vehicles. Use a helper, communicate with hand signals agreed in advance, back slowly, and if alone, get out and look (G.O.A.L.).

Question 17 of 20

Which lane is generally the best for a commercial vehicle on a multi-lane highway?

The far left (passing) lane
The middle lane
The right lane (slow lane)
Whichever has the lightest traffic

Correct. The right lane is generally best — it limits lane changes, reduces conflict with merging traffic only on the right, and matches commercial-vehicle speed.

Question 18 of 20

The blood-alcohol concentration (BAC) at or above which a CDL driver is considered to be driving under the influence in a commercial motor vehicle is:

Correct. The federal BAC limit for CDL drivers operating a commercial vehicle is .04 — half the .08 limit for non-commercial drivers in most states.

Question 19 of 20

A driver convicted of driving a CMV with a BAC of .04 or higher faces:

No penalty
A warning
Disqualification of at least one year for the first offense
License renewal

Correct. A first conviction of driving a CMV with BAC ≥ .04 disqualifies the driver for at least one year (three years if hauling hazmat).

Question 20 of 20

Which of the following is true about the front-end shock absorbers?

They have nothing to do with handling
Worn shock absorbers can cause poor handling and uneven tire wear
They are part of the brake system
They affect only ride comfort, never safety

Correct. Shock absorbers control suspension oscillation. Worn shocks contribute to poor handling, uneven tire wear, and reduced control on rough roads.

About the New Mexico 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 New Mexico Motor Vehicle Division 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 New Mexico CDL practice tests.