Wisconsin CDL Practice Test

Correct answer: 80% or more correct

Wisconsin states plainly that "a passing grade is 80% or more correct answers" on each CDL knowledge test — the federal standard applied to every section (General Knowledge, Air Brakes, Combination).

Correct answer: 50

WisDOT publishes the live counts: General Knowledge is 50 questions (covering manual Sections 1–3), Air Brakes is 25, and Combination (Combined Vehicles) is 20. You need 80% correct on each.

Correct answer: 18 years old

To get a Wisconsin CLP you must be at least 18, hold a valid Wisconsin driver license, pass the knowledge tests for your vehicle type, and have a valid federal medical card (without one, your CDL is restricted to intrastate driving).

Correct answer: 21 years old

You may not operate in interstate commerce — even with a CLP — unless you are at least 21 and have a federal medical certificate. Drivers aged 18 to 20 are limited to intrastate (within-Wisconsin) operation.

Correct answer: 180 days

A Wisconsin CLP is valid for 180 days and lists the vehicle types and endorsements you have qualified for. It is valid only to operate a CMV, and only for practice under the required supervision.

Correct answer: At least 14 days

You must have a CLP for 14 days before you are allowed to take a skills test. You must also pass all three segments of the skills test on the same CLP.

Correct answer: A qualified instructor or a person licensed for that class of CMV who is at least 21

A CLP holder must have a qualified driving instructor, or a person licensed to operate that type of CMV who is at least 21 years old, sitting next to them at all times. You also may not transport passengers with a CLP.

Correct answer: CDL intrastate only — you may drive only within Wisconsin

The K restriction limits you to intrastate commerce only — driving within Wisconsin. (The related 51 restriction is "intrastate only in an excepted industry.") A K- or 51-restricted CDL is valid only inside the issuing state.

Correct answer: An "L" restriction — no air-brake-equipped CMV

Skip the air brake tests and you get the "No air brake equipped CMV" (L) restriction — you may not legally operate a commercial vehicle with air brakes. A Z restriction applies if your skills test was taken with only partial air brakes.

Correct answer: Nothing — CDL knowledge tests are free

WisDOT states that "all knowledge tests are free" and no appointment is necessary at a DMV Customer Service Center. Allow enough time, though — the CDL knowledge tests take at least 1 to 1½ hours.

Correct answer: The heavier the vehicle, the more work the brakes must do and the more heat they absorb

The heavier the vehicle, the more work the brakes must do to stop it, and the more heat they absorb. Brakes, tires, springs, and shock absorbers on heavy vehicles are designed to work best when the vehicle is fully loaded.

Correct answer: Requires a greater stopping distance because it has less traction

It is a myth that empty trucks stop best. Empty trucks require greater stopping distances because an empty vehicle has less traction — the brakes and tires are designed to work best fully loaded.

Correct answer: Doubling it

Wet roads can double stopping distance. You must drive slower to be able to stop in the same distance as on a dry road.

Correct answer: By about one-third (for example, from 55 to about 35 mph)

Reduce your speed by about one-third on a wet road — for example, slow from 55 to about 35 mph. On packed snow, reduce speed by a half or more; on ice, reduce to a crawl.

Correct answer: By a half, or more

On packed snow, reduce speed by a half or more. If the surface is icy, reduce speed to a crawl and stop driving as soon as you can safely do so.

Correct answer: Reduce speed to a crawl and stop driving as soon as you safely can

If the surface is icy, reduce speed to a crawl and stop driving as soon as you can safely do so. Ice sharply reduces traction, so steering and braking become extremely difficult.

Correct answer: 30 mph if there is a lot of water

It does not take much water to cause hydroplaning; it can occur at speeds as low as 30 mph if there is a lot of water. It is more likely if tire pressure is low or the tread is worn.

Correct answer: Release the accelerator and push in the clutch to let the wheels turn freely

To regain control from hydroplaning, release the accelerator and push in the clutch to slow the vehicle and let the wheels turn freely. Do not use the brakes to slow down while hydroplaning.

Correct answer: Slow to a safe speed before you enter the curve

Slow to a safe speed before you enter a curve. Braking in a curve is dangerous because it is easier to lock the wheels and skid. Be in a gear that lets you accelerate slightly through the curve to keep control.

Correct answer: They can roll over at the posted speed limit for the curve

Tests have shown that trucks with a high center of gravity can roll over at the posted speed limit for a curve. Take a curve too fast and the tires may lose traction and skid off, or keep traction and roll the vehicle over.