Hawaii General Knowledge CDL Practice Test

This is a free 20-question practice test for the General Knowledge portion of the Hawaii 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 Hawaii Driver License Office 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 Hawaii.

Question 1 of 20

How many red reflective triangles must you carry in your commercial vehicle for emergency warning?

One
Two
Three
Six

Correct. You must carry three red reflective triangles, six fusees, or three liquid-burning flares for emergency warning use.

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

Doubling your speed roughly:

Doubles your stopping distance
Triples your stopping distance
Quadruples your stopping distance
Has no effect on stopping distance

Correct. Braking distance is proportional to the square of speed. Doubling speed roughly quadruples braking distance.

Question 4 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 5 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 6 of 20

Wet brakes can cause:

Reduced braking power, brakes pulling to one side, or wheel lockup
Better braking
No effect on the brakes
Improved fuel economy

Correct. After driving through deep water, brakes may be wet — they can lose effectiveness, pull to one side, or grab. Apply the brakes lightly while driving slowly to dry them.

Question 7 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 8 of 20

You are driving on a two-lane road. An oncoming driver drifts into your lane. You should:

Steer right onto the shoulder
Flash your high beams
Honk your horn
Brake hard and stop in your lane

Correct. When an oncoming driver drifts into your lane, the safer escape is right onto the shoulder. Steering left risks a head-on if the other driver corrects.

Question 9 of 20

You are driving on a wet road. To test how slippery the road is, you can:

Brake hard at 50 mph
Accelerate hard and listen for tire spin
Gently apply the brakes at low speed
Look at other vehicles' tires

Correct. At low speed and in a safe place, you can gently test traction by lightly applying the brakes or by gently accelerating. Hard braking at high speed is dangerous.

Question 10 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 11 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 12 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 13 of 20

A driver may resume driving after a 10-hour off-duty period only if:

They have not exceeded the on-duty hour limits and are not impaired
They feel rested
They have eaten
They have refueled

Correct. HOS rules limit driving and on-duty hours within a fixed window. After 10 hours off-duty, driving may resume only if other limits also allow.

Question 14 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 15 of 20

Which of these is NOT a hazard you should look out for ahead?

Pedestrians
A vehicle stopped on the shoulder
Roadway construction
A clear, dry road

Correct. Hazards are conditions that could lead to a crash: pedestrians, stopped vehicles, work zones, debris. A clear, dry road is the absence of a hazard.

Question 16 of 20

Hydroplaning is most likely to occur when:

Driving at low speed in light rain
Tires lose contact with the road and ride on water
Brakes are applied gently
Tires are over-inflated

Correct. Hydroplaning occurs when a film of water comes between the tires and the road, causing the tires to lose contact with the pavement. Higher speeds, worn tires, and standing water increase the risk.

Question 17 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 18 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 19 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 20 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.

About the Hawaii 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 Hawaii Driver License Office 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 Hawaii CDL practice tests.