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

A placarded vehicle must have at least ___ placards?

six

three

four

two

2 / 40

How often should air tanks be drained?

every 6 hours

every 4-5 days

once a day

every 7 days

3 / 40

You should check____when loading the small tanks of a cargo tank with bulkheads.

none of the answers listed

the fuel to air ratio

the weight distribution

the expansion rate

4 / 40

Select the answer that is not a part of the braking process when driving a tractor-trailer combination vehicle that has ABS:

you should monitor the tractor and trailer as you decrease your speed to keep control

only use the braking that is necessary to safely stay in control of the vehicle

you should drive at a higher speed to keep the trailer in line

you should brake in the same manner regardless of what you are driving

5 / 40

Your vehicle is going down a long hill and your brakes begin to fail. What should you do?

pump the brake pedal

put the gears in neutral

look for an escape ramp or an escape route

downshift

6 / 40

Select the true statement in regards to brake drums:

Hold the brake linings and shoes.

They are located at both ends of the axles of the vehicle.

They are bolted to the wheels.

All of these answers are correct.

7 / 40

You should___to reduce the air leakage rate.

release the service brake as the engine is running

release the service brake after turning off the engine

monitor the air pressure gauge as you press on the brake pedal

leave the engine running while charging the air system

8 / 40

How do you determine if slack adjusters need to be adjusted?

release the parking brakes and service brakes

pull out the automatic slack adjustment control knob

release the parking brakes and activate the service brakes

activiate the parking brake and service brake

9 / 40

What gauge on the dashboard indicates electrical system charging rate?

The coolant pressure gauge

The ammeter/voltmeter

The power gauge

The air gauge

10 / 40

The reason a bulk liquid tanker is hard to handle is:

Because the cargo has a low center of gravity.

Because of the high friction point.

Because the cargo has a high center of gravity.

Because the cargo has a high density.

11 / 40

For any flatbed load you must have at least ____ tie downs.

one

two

six

four

12 / 40

Select the two things that are important in preventing a rollover:

the length and weight of the vehicle

drive slowly around turns and keep the center of gravity of the cargo as high as possible

maintaining properly inflated tires and an even load on the trailer

drive slowly around turns and keep the cargo as close to the ground as possible

13 / 40

Which of the following statements about downshifting is NOT true?

downshift before entering a curve

downshift before starting down a hill

downshift when you get to the bottom of a hill

downshift before climbing a hill

14 / 40

You should check that the following makes an audible noise:

Air leaks

Radio system

Engine brakes

Electric or air horn

15 / 40

What does it mean when the safety valve releases air?

there is too much air in the air compressor

you need it to have it checked out by a mechanic because something is wrong

all of these answers are correct

pressure has passed 150 psi

16 / 40

Puddles or dripping fluids from the underside of the transmission and engine may indicate:

All of these answers are correct

Problems with the water pump

A leaking line or hose

A leak from the engine

17 / 40

Why are you required to take an exam about air brakes?

you cannot receive a CDL at all otherwise

it is a federal requirement

all trucks have air brakes

you would have to get a CDL with a restriction otherwise

18 / 40

A tractor should not be backed under a trailer until the whole air system is:

at a normal pressure

is between 50 and 80 psi

is between 40 and 60 psi

is at half of the maximum pressure

19 / 40

The most dangerous time during the school bus ride is:

When loading and unloading students.

Crossing railway crossing.

When the students become unruly on the bus.

On long bus journeys.

20 / 40

A commercial motor vehicle (CMV) is defined as:

a vehicle transporting hazardous materials

a vehicle with a gross weight over 26,001 lbs

a vehicle transporting 16 or more passengers

all of these answers are correct

21 / 40

The purpose for the emergency air line is:

supply air to the tractor air tanks and on combination vehicles controls the emergency brakes

none of the answers listed

supply air to the trailer air tanks and on combination vehicles, controls the service brakes

to supply air to the trailer air tanks and, on combination vehicles, controls the emergency brakes

22 / 40

Why should you cover cargo?

all of these answers are correct

because many states require it

to protect individuals from any spilled cargo

to protect your cargo from bad weather

23 / 40

A placard is required for a combustible liquid at?

110 gallons

1,001 pounds or more

100 gallons

Any amount

24 / 40

Which of the following statements about stopping distances is NOT true?

empty trucks require greater stopping distances because they have less traction

trucks traveling on ice or snow require greater stopping distances

brakes, tires, springs and shocks are designed to work best when the truck is empty

trucks traveling at higher speeds require greater stopping distances

25 / 40

What is most likely to occur when driving a set of doubles and a set of trailer wheels goes into a skid?

the rig will slide sideways but stay in a straight line

no matter how you turn the steering wheel, the rig will continue in a straight line

there will be a trailer jackknife

nothing will occur

26 / 40

This object should not have any missing parts, be fully raised, the crank handle is secured, and that there is no damage to the frame.

Landing gear

Release arm

Lifts/doors/tires

Drop arm

27 / 40

Select the true statement:

A "bobtail" tractor will take longer to stop than a combination vehicle that is fully loaded down to the maximum weight.

Wait as long as possible to brake when driving a heavy vehicle.

Lighter vehicles requiring more braking power to stop compared to heavier vehicles.

None of the answers listed.

28 / 40

Select what you should not do when coupling the glad hands.

make sure to match the colors or check the tags before connecting

press the seals together at a 90 degree angle

cross the air supply lines to test for leaks

clean the couplers before connecting them

29 / 40

What do you do first during step 3 of starting the engine and inspecting the inside of the cab?

Shift the gear to neutral.

Start the engine after getting in the cab.

Listen for any unsual noises after starting the engine.

Make sure the parking brake is activated after getting in the cab.

30 / 40

How do you check the air compressor governor "cut in" and "cut out" pressures?

monitor the air pressure gauge

decrease the tank pressure by stepping on and off the brake

all of these answers are correct

run the engine at a fast idle

31 / 40

Air tanks need to be drained:

to prevent water and oil from building up in the tank

to keep the tanks cold when not in use

to keep the tanks warm when not in use

air tanks should absolutely never be drained

32 / 40

The gauge that needs to come up to normal levels after starting the engine within a few seconds is _____.

blood pressure

oil temperature

air brake pressure

oil pressure

33 / 40

What does the air compressor governor control?

when the air is taken out of the hoses

when the valve system releases pressure

when air pressure is applied to the brakes

when air is pumped into the air tanks

34 / 40

What is the value of the overhead rear-view mirror inside of the bus?

To monitor the driver's appearance.

To monitor passenger activity.

To provide visibility directly in the back of the bus.

To check blind spots.

35 / 40

What is the stopping distance for a tractor trailer that is traveling at 55 mph on dry pavement?

about 300 feet which is about a football field length

about 200 feet which is 2/3 of a football field

about 600 feet with is about two football field lengths

about 150 feet which is 1/2 of a football field

36 / 40

You should expect____when backing a tractor under a trailer.

the trailer to be completely still

the end of the kingpin to be level with the top of the fifth wheel

the trailer to lift slightly

the trailer landing gear to be fully extended

37 / 40

The transport index of a radioactive material:

Tells the degree of control needed during transportation.

None of these answers are correct.

Is something that only the shipper needs to worry about.

Is another way of writing the weight of the package.

38 / 40

This carries hydraulic fluid or air to the wheel brake assemby.

Connector rods

Brake drums

Brake lines/hoses

Slack pieces

39 / 40

The shipping papers for hazardous materials can be found:

In a pouch on the driver's door.

On the driver's seat when out of the vehicle.

Any of the above locations.

In clear view, within reach while driving.

40 / 40

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

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 brake pedal until the air pressure drops below 20 psi

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

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

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

CDL Category Practice Tests

CDL Practice Test

How To Get An iowa Commercial Drivers License

Hit the Open Road

iowa CDL License Test Tips

Additional Information

Information on the Iowa Department of Transportation

Additional Iowa CDL Helpful Links

iowa
CDL Practice Test