iowa
CDL Practice Test

Below are practice questions for the Iowa CDL test. The site is free and you are able to take the practice test as many times as you need to as you prepare to obtain your Iowa CDL. The questions and answers covered in these Iowa practice CDL tests are taken from the Iowa DOT CDL manual. You will be presented with 40 questions and you must answer 34 questions correctly to pass. There is a 50-minute time limit. You may not go back once you answer a question. Click the "Start Test
" button below to begin.

1 / 40

It is very important that you never smoke around which hazard classes?

All hazard classes.

Corrosive, radioactive, dangerous, slippery when wet, inhalation.

It is ok to smoke anywhere.

Explosives, flammable gas, oxidizers, flammable solids, flammable liquids.

2 / 40

When should you check your mirrors for a lane change?

After completing the lane change.

Right after starting the lane change.

Before and after signaling the change.

All of these answers are correct.

3 / 40

What is a technical name?

The name for a hazardous material most commonly used in the trucking community, accepted as standard.

The name for a hazardous material most commonly used on the street.

The medical term for hazardous materials used by medical personnel.

The name for a hazardous material used in scientific journals and texts, recognized as its chemical and microbiological name.

4 / 40

Select the true statement in regards to managing the space to the sides:

you should try to avoid driving next to others when possible

you should always keep your vehicle to the right side of the lane

high wind gusts will not cause any issues for doubles or triples

you should drive down the center of both lanes over the pavement markings

5 / 40

The locking jaws of the kingpin should close around:

the tip

the shank

the base

the apex

6 / 40

Overhead inside mirror is used to:

monitor traffic that approaches and enters the blind spot area

see the blind spot immediately behind the bus

see the area where students exit the bus

see all of the students

7 / 40

_____ create a little above 90 degree angle between the adjuster arm and push rod when the brakes are released and no less than 90 degrees when the brakes are applied.

slack adjusters

brake drums

air lines

brake disc

8 / 40

The air leakage rate for a combination vehicle should not exceed ____psi a minute.

9 / 40

Water is drained from the compressed air tanks because:

to keep the oil in the air compressor clean

the water will over cool the compressor

braking power is decreased due to the low boiling point of water

the water could freeze in cold weather and cause braking failure

10 / 40

Bus drivers must have a CDL if they drive a vehicle:

That has air brakes.

That is designed to carry more than nine passengers.

That has a gross weight rating of more than 26,000 pounds.

Designed to seat more than 16 or more persons, including the driver.

11 / 40

How often should you drain your air tanks?

at the end of each shift

at the beginning of each month

at the end of each trip

at the end of each week

12 / 40

Animals and human foodstuffs should not be loaded in the same vehicle with?

Flammable gases

Poisons

Explosives

Flammable liquids

13 / 40

A drawbridge does not have a traffic light showing green or a traffic control attendant. How many feet before the draw of a bridge must a bus driver stop?

At least 75 feet.

At least 100 feet.

At least 25 feet.

At least 50 feet.

14 / 40

What is the purpose of a baffle?

It stops side to side surging.

It allows you to haul loads that are mixed.

It makes it easier to clean the tanker out.

It controls the surge of liquid forward and backwards.

15 / 40

You need to raise the landing gear just to the height of where it clears the pavement before driving.

only in ideal conditions

true

only in raining conditions

false

16 / 40

How often should you check the tires if your placarded trailer has dual tires?

Check tires every hour or 75 miles.

Check tires every 2 hours or 100 miles.

Check tires every 3 hours or 150 miles.

Check tires every 4 hours or 200 miles.

17 / 40

What is the minimum amount of distance you should maintain when driving at 50 mph in ideal conditions with a 100 ft twin trailer combination?

8 seconds

6 seconds

13 seconds

11 seconds

18 / 40

Select why you should not use the trailer hand valve while driving:

there is a possibility it will make the trailer skid

you should only ever use the parking brake

it does not work as well as the foot brake does

it will cause the tractor to shake

19 / 40

When approaching railroad tracks, stop your bus:

15 and 50 feet before railroad crossings.

5-10 feet before railroad tracks.

Only if you have manual transmission, then proceed with flashers on.

On the tracks so you can see if the train is coming.

20 / 40

Which of the following is a clue another driver is impaired:

All of these answers are correct.

Stopping at a green light, or waiting too long at a stop.

Open window in warm weather.

Exiting the interstate when there's no gas station visible.

21 / 40

A driver of a tank vehicle should take curves, off ramps, and on ramps at a speed lower than the posted speed limit.

True but only in ideal conditions

True

True but only in rainy conditions

False

22 / 40

Which hazard classes must you NEVER smoke, or perform any activity involving fire, within 25 feet of?

Class 2 only

Class 1 only

Classes 1, 2, 3, and 4

Class 4 only

23 / 40

Which of the following hazard classes utilizes a transport index in order to determine how much of it can be loaded on a single vehicle for transport?

Class 7—radioactive materials

Class 1—explosives

Class 4—live chickens

Class 3—flammable liquids

24 / 40

How do you know when your brakes are fading?

your speed increases when pressure is removed from the brake pedal

to control your speed on a downgrade you have to push harder on the brake pedal

to control your speed on a downgrade you have to apply less pressure to the break pedal

the brake pedal flops to the cabin floor

25 / 40

What color are all school buses painted?

The individual district decides the exact color.

Florescent yellow.

Orange yellow.

National school bus yellow.

26 / 40

A battery box check is important. The battery must be secure, connection must be tight, and cell caps must be present. In addition these items should be checked:

Battery connection should show signs of excessive wear.

Battery connections should not show signs of excessive corrosion, and the battery box and cover or door should not be damaged and should be secure.

Battery connections should not show signs of excessive corrosion, but the battery box and cover or door is unimportant.

The fluid level inside the battery.

27 / 40

When driving on a clear night with the vehicle lights on, your speed should be such that you can stop within _____.

2 times the length of your vehicle

the length of half a football field

the distance you will travel in 10 seconds time

the distance you can see ahead of you

28 / 40

How do you check the connection after locking the kingpin into the fifth wheel?

pull the tractor ahead gently with the trailer brakes locked down

pull the tractor at a sharp right to release the trailer brakes

pull forward 25 feet, turn to the left, and then to the right

pull forward 25 feet, turn to the right, and then to the left

29 / 40

A vehicle placarded for Division 1.1, 1.2, or 1.3 explosives:

May be left unattended in a safe haven.

May never be parked on private property.

May not be parked on the cosignee's property.

May never be left unattended under any condition.

30 / 40

The emergency air line is _____and the service air line is____.

white, blue

red, green

yellow, white

red, blue

31 / 40

Select the true statement in regards to an application pressure gauge:

when accelerating it releases air

it shows how much air pressure you are applying to the brakes

it is connected to the generator

it prevents the brakes from failing

32 / 40

Select the true statement about stop valves in a cargo tank:

They are manually operated.

They will fall off in an emergency.

They will close in an emergency.

They protect the piping and tank during rear end collisions.

33 / 40

If you are drowsy, you should _____ before you drive.

do a little exercise

get sleep

take a cold shower

drink coffee

34 / 40

When conducting a pre-trip inspection, the most important item to verify is _____.

that there are no leaks in the air brake system

that the tire tread is sufficient for the expected driving conditions

that the radio transmits a signal

that the registration is in the cup holder

35 / 40

A leak rate for a straight truck or bus air brake system should not exceed _____psi per minute when the engine is off and the brakes are released.

36 / 40

Why does it take special skills to haul a tank vehicle?

All of the answers listed.

There is a high center of gravity.

It is top heavy.

The weight of the load is high up off the road.

37 / 40

What is always required before loading, driving, or unloading a tanker?

Shift into park

An inspection

Registration of driving plan

Clean the vehicle

38 / 40

How do you test your service brakes?

pull over and activate the parking brake

release the air pressure and activate the parking brake

after releasing the parking brake, move forward slowly and apply pressure to the brake pedal

apply pressure to the brake pedal when moving at highway speeds

39 / 40

Which of the following is a key steering component?

torque rod

gear box

leaf spring

bearing plate

40 / 40

Select the true statement in regards to what the fifth wheel should be checked for.

if it is properly greased

if the jaws are open

if there is any missing or damaged parts

all answers listed

Your score is

The average score is 0%

5/5 - (1 vote)

CDL Category Practice Tests

CDL Practice Test

How To Get An iowa Commercial Drivers License

Individuals may apply for their CDL starting at age 18. To be eligible for interstate driving as well as HazMat and Doubles/Triples applicants must be 21 years of age or older. All individuals applying for an Iown CDL must present a Medical Examiner’s Certificate according to the United States Federal Regulations.

If any one of the descriptions below is true about an applicant, they will be disqualified from receiving their CDL.

Driver posses more than one driver’s license.
Driver was convicted of driving under the influence in the past 24 months.
Driver has a suspended, denied, canceled, or revoked driver’s license.

Endorsements
H – Hazardous Materials
N – Tank Vehicle
T – Doubles/Triples
X – Hazmat and Tank Comb
P – Passenger Vehicle
S – School Bus

Drivers must take a knowledge test as well as a practical skills test to showcase their knowledge of commercial driving laws and their ability to operate a commercial vehicle.

Hit the Open Road

iowa CDL License Test Tips

Applicants must complete a general knowledge test to display their understanding of commercial driving laws. The general knowledge exam is comprised of 50 questions. Those seeking a Class A CDL will need to complete an additional 20 question test on combination vehicles. Applicants seeking additional endorsements will need to take an additional test on the endorsement topic. The Passenger, Tank, and Doubles/Triples Endorsements are 20 question tests. Removing the Air Brake Restriction, the Iowa Operator and School Bus Endorsements are 25 questions. The Hazmat Endorsement is a 30 question test. All applicants must pass the respective assessments with a score of 80 percent or better to receive their Iowa CDL permit.

A skills assessment is required of all applicants. This assessment is comprised of three parts, which are the pre-trip inspection, basic controls skills, and on-road driving. Individuals applying for their P and S endorsements will be required to take the skills test in the respective vehicle for their endorsement.

Additional Information

Information on the Iowa Department of Transportation

The Iowa Department of Transportation administers CDL requirements and testing in Iowa. To get more information contact them via:

Website: https://iowadot.gov/DriversVehicles#CommercialDrivers

Phone: 515.239.1101

Additional Iowa CDL Helpful Links

Please use the links below to access more valuable Iowa CDL testing resources and to learn more about practice driving tests for the state of Iowa.

iowa CDL Practice Test