Wisconsin General Knowledge CDL Practice Test

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

Question 1 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 2 of 20

What is the only effective way to remove alcohol from the body?

Drinking coffee
Cold showers
Eating a heavy meal
Time

Correct. Only time eliminates alcohol from the body — at roughly one drink per hour. Coffee, food, and showers do not speed up the process.

Question 3 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 4 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 5 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 6 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 7 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 8 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 9 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 10 of 20

A fully loaded tractor-trailer traveling at 55 mph on dry pavement requires roughly what total stopping distance (perception + reaction + braking)?

100 feet
200 feet
300 feet (about the length of a football field)
600 feet

Correct. Total stopping distance for a heavy commercial vehicle at 55 mph on dry pavement is approximately 300 feet, or the length of a football field including end zones.

Question 11 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 12 of 20

To recover from a drive-wheel skid, you should:

Brake harder to slow down
Steer in the opposite direction of the skid
Stop accelerating, push in the clutch, and counter-steer
Apply the parking brake

Correct. Stop applying power, push in the clutch (or shift to neutral) to let the wheels turn freely, and counter-steer in the direction you want the front of the vehicle to go.

Question 13 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 14 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 15 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 16 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.

Question 17 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 18 of 20

When you exit a highway in a heavy commercial vehicle, you should:

Maintain highway speed onto the ramp
Slow down before reaching the ramp curve, since posted advisory speeds assume cars
Speed up to clear the ramp
Brake only at the bottom

Correct. Posted ramp speeds assume passenger cars. A loaded heavy vehicle, especially with high CG, can roll over at the posted speed. Slow before the curve.

Question 19 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 20 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.

About the Wisconsin 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 Wisconsin 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 Wisconsin CDL practice tests.