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

These tires should have a minimum tread depth of 4/32 inches.

Drive axle tires

Steering axle tires

Non-steering axle tires

Donut tires

2 / 40

What is the service air line controlled by?

the relay vavle by sending air pressure from the trailer air tank to the trailer brake chambers

the pressure applied to the trailer hand brake or by the foot brake

all answers listed

the relay valve that connects the trailer air tanks to the trailer air brakes

3 / 40

Which signals may be used to warn of a stopped vehicle that contains explosives?

Flares or fuses

Reflective triangles

All of these answers are correct

Signal fires

4 / 40

You must keep shipping papers describing hazardous materials ______.

in a pouch on the driver’s door or in clear view within immediate reach while the seat belt is fastened while driving on the driver’s seat when out of the vehicle

in a pouch on the drivers door or in the overhead compartment above the driver’s seat only

within 100 feet of the hazardous materials at all times

with the bills of lading

5 / 40

How often should you check the cargo you are transporting?

within the first 50 miles after beginning a trip

every 150 miles or every three hours

after every break you take during driving

all of these answers are correct

6 / 40

Do empty trucks have the best braking?

yes

yes, but only on wet surfaces

yes, but only if the truck is newer than 1998

7 / 40

Which of the following is the most important reason for doing a pre-trip inspection?

to make sure nothing has been stolen from the vehicle

because other drivers do it

to make sure the vehicle will make your destination

safety for yourself and other road users

8 / 40

What are shippers trying to accomplish when they package the material?

Make it easy to open and close.

Make it easy to identify.

Make it as light as possible.

All of these answers are correct.

9 / 40

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

May not be parked on the cosignee's property.

May never be parked on private property.

May never be left unattended under any condition.

May be left unattended in a safe haven.

10 / 40

Secure baggage and freight in ways that avoid damage and:

All of these answers are correct.

Protect riders from injury if carry-ons fall or shift.

Allow the driver to move freely and easily.

Allow riders to exit by any window or door in an emergency.

11 / 40

Which of these statements about speed management and braking is true?

You need about four times as much stopping distance at 40 mph as at 20 mph.

The posted speed limit will always allow you to stop safely.

The total stopping distance of a bus is the distance it takes to stop once the brakes are applied.

Stopping time increases by one second for each 10 mph over 20 mph.

12 / 40

The bus driver must accept responsibility for supervising and controlling students while on the bus route. Who is the person in charge?

The school district superintendent.

Bus driver.

Students on the bus.

Parents of the students on the bus.

13 / 40

Select which vehicles are required to have a low air pressure warning signal:

they are optional

all operating vehicles with air brakes

all vehicles built after 2005

all vehicles built after 2010

14 / 40

If you must stop on the shoulder of the road, you should place warning devices at all of the following places except...

about 100 feet in front of your vehicle

about 100 feet behind your vehicle

on the other side of a divided highway

within 10 feet of the front or rear corners

15 / 40

How much space should you see between the lower and upper fifth wheel when checking the coupling of a converter dolly?

1 to 1 1/2 inches

none

it depends on how heavy the load is

1/2 to 1 inch

16 / 40

Five hazard classes that require placarding in any amount are ______.

explosives 11, corrosive 8, flammable 3, explosives 14, and poison 61

none of these answers are correct

poison gas 23, dangerous when wet 43, explosives 13, explosives 12, and explosives 11

corrosive 4, hazardous 14, flammable 2, explosives 7, and radioactive 12

17 / 40

Select the false statement about tractor protection valves.

the trailer air supply valve in the cab controls it

should the trailer air leak, it keeps the air in the tractor

air is allowed to leak from the tractor line when it is closed

if the air pressure is low it will automatically close

18 / 40

Select the statement that is true in regards to quick steering movements and triple/double trailers:

as you perform quick steering movements you should apply pressure to the brake pedal

it is easier to countersteer compared to other vehicles

there are no issues that occur from quick steering

they flip over due to quick steering movements a lot easier than other vehicles

19 / 40

For Division 1.1 or 1.2 Explosives A, should the floor liner required be stainless steel?

Never use a floor liner for any explosive class

Any type of floor liner is sufficient

Yes

20 / 40

The two other places where the hazardous identification number must appear are:

On the gas tank and a sticker in the glove compartment.

On the back of the truck and inside the glove compartment.

Any bulk packaging and the cargo tanks.

On a temporary license plate holder and the steering wheel.

21 / 40

When approaching railroad tracks, stop your bus:

5-10 feet before railroad tracks.

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

15 and 50 feet before railroad crossings.

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

22 / 40

Drivers placard their vehicle to _____ the risk.

elevate

communicate

minimize

take away

23 / 40

Liquid surge affects the handling of a tanker by:

Decreasing the wind drag.

Allowing you to take tighter turns.

Moving the truck in the direction of liquid flow.

Allowing you to stop faster.

24 / 40

What is most likely to occur when driving a tanker truck and the front wheels begin to skid?

No matter how you steer, you will continue in a straight line.

The surge will disconnect the tank from the truck.

The tank will roll over.

Nothing will occur.

25 / 40

In what location must you keep your shipping papers which describe any hazardous materials?

On the driver's seat anytime you are outside of the vehicle.

In a fire-safe pouch under the passenger seat while you are driving.

In a fire-safe pouch under the driver's seat that you can reach while you are driving.

In a locked glove compartment anytime you are outside of the vehicle.

26 / 40

If hazardous material is spilling from your vehicle, do not move your vehicle:

Any more than safety required.

In an upwind direction.

Any more than 500 feet.

Any more that 450 feet.

27 / 40

The bolst, brackets, or bushings that attach the air bag and/or spring to the vehicle and axle frame are _____.

spring mounts

shock dampeners

none of the answers listed

lug bolt

28 / 40

The brake pushrod should not move more than____for manual slack adjusters.

1-2 inches while the brakes are set

movement is not allowed

checking is not required in vehicles built after 1994 as they have automatic slack adjusters

an inch when pulled by hand with the brakes released

29 / 40

How should you know when to shift?

road speed and wind speed

every 3 to 5 seconds or engine speed

engine speed and the shift indicator light

engine speed and road speed

30 / 40

Water is drained from the compressed air tanks because:

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

the water could freeze in cold weather and cause braking failure

the water will over cool the compressor

to keep the oil in the air compressor clean

31 / 40

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

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

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

That is designed to carry more than nine passengers.

That has air brakes.

32 / 40

Where is compressed air stored?

in the compartment for the engine

in the hose lines

in the storage tank

in the gasoline tank

33 / 40

The best way to test the low air pressure warning signal is to:

manually release the air out of your brakes to see if the signal activates

apply pressure on and off the brake pedal until the air pressure drops below 20 psi

apply pressure on and off the brake pedal with the engine off to drop the air pressure to below 60 psi

apply pressure on and off the brakes while the engine is running

34 / 40

If you double your speed, what will happen to your stopping distance?

it increases by four times

it stays about the same

it increases by two times

none of these answers are correct answers are correct

35 / 40

When not towing a trailer, why should the tractor glad hands be locked?

it keeps water and dirt out of the lines

the connected brake circuit will become a back up air tank

this should never be done

the system pressure will not build up

36 / 40

Tankers used to transport hazardous materials on vehicles must be marked with:

The date of manufacture.

The chemtrec phone number.

The owner's puco or icc number.

The un or na id number of the product.

37 / 40

What product is typically carried in a liquid tank trailer without baffles?

Fuel.

Food or milk products.

Fertilizer.

Hydrogen peroxide.

38 / 40

Which of the following statements about overhead space is true?

warning lights are always installed on low bridges and overpasses

an empty van is lower than a loaded one

the heights posted at bridges are usually accurate

the weight of the cargo changes a truck's height

39 / 40

This gauge will indicate if the generator or alternator is charging:

Voltmeter/ammeter

Oil pressure

Coolant

Gas tank

40 / 40

What will happen right away should the service air line come apart but the emergency line is intact while driving a combination vehicle?

the trailer's air tank will leak through the one line

the emergency tractor brakes will activate

you will come to a complete stop

nothing will occur until you try to use the brakes

Your score is

The average score is 55%

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.

Cookie	Duration	Description
cookielawinfo-checkbox-analytics	11 months	This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Analytics".
cookielawinfo-checkbox-functional	11 months	The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional".
cookielawinfo-checkbox-necessary	11 months	This cookie is set by GDPR Cookie Consent plugin. The cookies is used to store the user consent for the cookies in the category "Necessary".
cookielawinfo-checkbox-others	11 months	This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other.
cookielawinfo-checkbox-performance	11 months	This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Performance".
viewed_cookie_policy	11 months	The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. It does not store any personal data.

iowa CDL Practice Test