New Hampshire General Knowledge CDL Practice Test

This is a free 20-question practice test for the General Knowledge portion of the New Hampshire 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 Hampshire 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 New Hampshire.

Question 1 of 20

You are driving a 40-foot vehicle at 35 mph. The minimum following distance you should maintain is:

2 seconds
3 seconds
4 seconds
7 seconds

Correct. The rule of thumb: 1 second per 10 feet of vehicle length below 40 mph. A 40-foot vehicle therefore needs 4 seconds of following distance.

Question 2 of 20

Which of the following can cause the wheels of your vehicle to skid on a curve?

Driving below the posted speed limit
Driving too fast for the curve
Slowing down before entering the curve
Driving with a light load

Correct. Posted curve advisory speeds assume cars; a heavy commercial vehicle with a high center of gravity may roll over or skid even at the posted speed. Slow before the curve, accelerate gently through it.

Question 3 of 20

If your vehicle hydroplanes, what should you do?

Brake hard immediately
Steer sharply to recover
Release the accelerator and push in the clutch
Accelerate to push through

Correct. Release the accelerator and push in the clutch. Do not brake or steer hard until the tires regain contact.

Question 4 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 5 of 20

The most important reason for doing a vehicle inspection is to:

Comply with the law
Save fuel
Find safety problems before they cause a crash
Document mileage

Correct. A pre-trip inspection is meant to find problems that could cause a crash or breakdown. Compliance is a side effect, not the purpose.

Question 6 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 7 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 8 of 20

When driving down a long, steep downgrade, you should:

Hold the brakes lightly the whole way down
Select the proper gear before starting down and use intermittent firm brake applications
Coast in neutral
Use only the engine brake

Correct. Select a low gear before starting down. Use the brakes in firm, intermittent applications: brake until 5 mph below safe speed, release until safe speed is regained, repeat. Continuous brake application overheats the brakes.

Question 9 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 10 of 20

Which of the following is a good way to avoid hydroplaning?

Drive faster
Use cruise control in the rain
Slow down on wet roads, especially when standing water is visible
Over-inflate the tires

Correct. Slowing down reduces the chance of hydroplaning. Maintain proper tire inflation and tread depth, and avoid using cruise control on wet roads.

Question 11 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 12 of 20

Which of the following is a cab in-vehicle inspection item?

Steering wheel free play
Headlights
Tire condition
Lug nuts

Correct. Steering-wheel free play is checked from the driver seat and should not exceed 10 degrees (about 2 inches on a 20-inch wheel).

Question 13 of 20

When should you place reflective triangles on a divided highway after stopping due to a breakdown?

10, 50, and 100 feet behind the vehicle
10 feet to the rear, 100 feet to the rear, and 200 feet to the rear
10, 100, and 200 feet to the rear, on the traffic side
100, 200, and 500 feet to the rear

Correct. On a divided highway with traffic from one direction, place triangles 10, 100, and 200 feet behind the vehicle, on the shoulder or in the lane you stopped in.

Question 14 of 20

Most drivers who fall asleep at the wheel:

Are aware they are tired and pull over
Do not realize they are about to fall asleep
Have been drinking
Have been on the road less than an hour

Correct. Most drivers who fall asleep do not realize how drowsy they are. The only fix is to stop and rest before fatigue reaches that point.

Question 15 of 20

You are driving a 60-foot tractor-trailer at 55 mph. The minimum following distance you should maintain is:

4 seconds
5 seconds
6 seconds
7 seconds

Correct. Above 40 mph, add one extra second to the per-10-foot rule. A 60-foot vehicle = 6 seconds + 1 = 7 seconds at 55 mph.

Question 16 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 17 of 20

Which of the following is NOT part of the seven-step pre-trip inspection method?

Approach the vehicle and overview
Check the engine compartment
Test the AM/FM radio
Walk around inspection

Correct. The radio is not part of the safety inspection. The seven-step method covers approach, engine compartment, in-cab checks, lights, walk-around, signal lights, and brake checks.

Question 18 of 20

Which of these is the best advice for staying alert on a long trip?

Drink coffee
Take cold pills
Get enough sleep before the trip and take rest breaks
Open the window

Correct. Adequate sleep before driving and scheduled rest breaks are the only reliable strategies. Coffee and cold air mask fatigue but do not eliminate it.

Question 19 of 20

Which type of fire extinguisher should you use on an electrical fire?

Class A
Class B
Class C
Class D

Correct. Class B:C dry-chemical extinguishers (often labeled "B:C" or "ABC") are appropriate for electrical fires. Never use water on an electrical fire.

Question 20 of 20

Maximum allowable steering-wheel play is approximately:

5 degrees
10 degrees
20 degrees
30 degrees

Correct. Steering wheel play should not exceed 10 degrees (roughly 2 inches on a 20-inch wheel). More than that, the vehicle is hard to steer.

About the New Hampshire 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 Hampshire 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 New Hampshire CDL practice tests.