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

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

To provide visibility directly in the back of the bus.

To monitor passenger activity.

To monitor the driver's appearance.

To check blind spots.

2 / 40

The minimum tread depth for steering axle tires is:

None of the answers listed

2/23 inch

14 mm

4/32 inch

3 / 40

What is the first thing to do if your vehicle catches fire while driving?

find a service station to pull into

open the hood and let the flames die down

pull off the road and park in an open area

open the door and jump out of the vehicle

4 / 40

An example of a low pressure warning signal for air brakes is:

a buzzer

a wig wag mechanical arm

red light

all of these answers are correct

5 / 40

Which trailer is more likely to roll over when pulling 3 trailers?

the first trailer

the tractor

the second trailer

the last trailer

6 / 40

What is a passive railway crossing?

The type of crossing on which the driver does not have to stop.

The type of crossing, which does not have any type of traffic control device.

The type of crossing with no cross buck sign.

The type of crossing where you can pass the tracks without stopping.

7 / 40

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

Yes

Never use a floor liner for any explosive class

Any type of floor liner is sufficient

8 / 40

How much space should there be between the lower and upper fifth wheel?

1/4 to 1/2 of an inch

it is dependent on the load you are carrying

zero

1 to 2 inches

9 / 40

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

Non-steering axle tires

Donut tires

Drive axle tires

Steering axle tires

10 / 40

Urban mass transit coaches may have a brake and accelerator interlock system. Which of the following statements is true?

The interlock applies the brakes and holds the throttle in idle position when the rear door is open.

The interlock releases when you close the rear door.

Do not use this safety feature in place of the parking brake.

All of these answers are correct.

11 / 40

What is the service air line controlled by?

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

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

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

all answers listed

12 / 40

How do you test the trailer service brakes?

apply pressure to the brake pedal

release air to the spring brakes

apply the hand control and check to see if you feel the trailer brakes come on

test the brakes out while driving at 5 mph

13 / 40

What should you check for when inspecting a converter dolly?

that the safety chains are secured to the trailer

that the converter dolly air tank drain valve is in the closed position

all answers listed

that the spare tire is secured if there is one

14 / 40

When accelerating:

always use the parking brake to slow down

do not engage the clutch before you take your foot off the brake

speed up smoothly and gradually and avoid jerking

"hammer down" when your wheels start to spin

15 / 40

The trailer height is correct for connecting a converter dolly to a second or third trailer when:

all answers listed

the center of the kingpin is past the locking jaw

the trailer will rise slightly when the converter dolly is backed underneath it

the kingpin is over the fifth wheel

16 / 40

Select the false statement about suspension:

Check to make sure torsion bars and/or arms are lubricated.

Check for shifted, missing, or cracked leaf springs.

Check for distorted or broken coil springs.

Check for broken or cracked spring hangers.

17 / 40

Where are the two main places where the hazardous material identification number appears?

On the package and on paperwork at the shipping point of origin.

On the shipping papers and on a secret document in the driver's wallet.

On the shipping papers and on the package.

On the package and on paperwork at the shipping destination.

18 / 40

Why is the proper adjustment and use of all mirrors so vital to the safe operation of the school bus?

In order to clear up blind spots around the bus.

In order to see if small vehicles are driving in the bus blind spots.

In order to observe the danger zones around the bus and look for the students, traffic, and other objects in this area.

In order to observe the danger zones around the bus.

19 / 40

A tank vehicle:

All answers listed.

Is a vehicle that can transport liquid.

Is a vehicle that can transport bulk fertilizer.

Is a vehicle that can transport liquified gasses.

20 / 40

In the event of an accident you should remember to do the following EXCEPT:

move the victims out of the way immediately

protect the area

stop any bleeding and keep the victims warm

notify authorities

21 / 40

You should follow the posted speed limits for curves and be aware of:

A rollover may occur even when driving at the posted speed limit.

All answers listed.

The higher center of gravity on a tank truck.

The posted speed limit may be too high for safety.

22 / 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

the brake pedal flops to the cabin floor

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

23 / 40

What will happen should a driver cross the air lines when hooking up the an older trailer?

none of the answers listed

the brake pedal will activate the trailer spring brakes instead of the air brakes

if there are no spring brakes, you can drive on but there will be no trailer brakes

the hand valve will activate the tractor brakes instead of the trailer brakes

24 / 40

While completing the 1st component of the air brake check you are required to fully push down on the foot brake and _____.

see if the air pressure drops more than 3 lbs in a minute while holding it down for that full minute in a single vehicle

see if the air pressure drops more than 4 lbs in a minute while holding it down for a full minute in a combination vehicle

both of the answers listed

none of the answers listed

25 / 40

What is the purpose of the supply pressure gauge?

to inform you of how much air is in the tank

to inform you if there is too little air in the tank

to inform you about how hot the air in the tank is

all of these answers are correct

26 / 40

At 55 miles-per-hour it takes about 6 seconds to stop a fully loaded truck and the braking distance is:

about 1/4 mile

about two car lengths

about the length of a football field or 100 yards

about two truck lengths

27 / 40

Which of the following is NOT a basic step to be taken at a crash scene?

notify authorities

gather the contact information of all the drivers involved

protect the area

care for the injured

28 / 40

The Emergency Response Guide, ERG, can best be explained as _____.

a guide explaining what materials can be hauled together in the same vehicle

a guide explaining what materials can be hauled together in the same vehicle and a guidebook for firefighters, police, and industry workers on how to protect themselves and the public from hazardous materials

a guidebook for firefighters, police, industry workers, truck drivers, dock workers, and shippers on how to protect themselves and the public from hazardous materials

none of these answers are correct

29 / 40

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

it is connected to the generator

when accelerating it releases air

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

it prevents the brakes from failing

30 / 40

Select the true statement in regards to the liquid inside of a bulk tank causing a tank truck to roll sideways.

It can occur even when driving at the posted speed limit.

It can occur even with baffles inside that slow the flow.

It can occur when driving through a curve.

All answers listed.

31 / 40

A truck with baffles will handle:

The same as a tanker with no baffles.

Heavier that it actually is.

None of the answers listed.

With less front to back surge compared to trailers without baffles.

32 / 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 50 feet.

At least 25 feet.

At least 75 feet.

At least 100 feet.

33 / 40

When approaching a school bus stop, you should:

Activate your overhead amber lights.

All of these answers are correct.

Gradually decrease speed until the stop.

Continuously check all mirrors.

34 / 40

What is the safest way to stop unruly behavior on the bus?

keep checking the rear view mirror so you can see what happened and report to the principal

have the unruly students move to the front of the bus

yell loudly for the students to sit down and behave themselves

pull off the road in a safe location, secure the bus, stand up, and tell the students what behavior you expect of them

35 / 40

The container for the mechanism that transforms the steering column action into wheel action is:

Air brake system

Steering hoses/box

Locking pin

Steering linkage

36 / 40

Select the correct setup for shut-off valves:

the front and back shut-off valves are open

the rear shut-off valves are closed and the front trailer valves are open

the front shut-off valves are closed and the rear trailer valves are open

the front and back shut-off valves are closed

37 / 40

Select the true statement about slack adjusters:

they should only be adjusted by a mechanic that is certified in slack adjusters

they do not ever need to be adjusted

they can be adjusted automatically or manually

they should move a minimum of 2 inches from the push rod attachment

38 / 40

Select the true statement about what the Air Compressor Governor controls:

it controls when the air compressor pumps air into the storage tanks

it controls when the brakes will be applied

it controls when the warning system is activated

it controls when air is released from the storage tank

39 / 40

Rods, connecting links, and arms from the steering box to the wheel are a part of the:

CB radio

Power steering fluid

Braking system

Steering linkage

40 / 40

What is the best way to see the sides and rear of your vehicle?

your mirrors

rear view cameras

all of these answers are correct

a helper

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