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The CDL general knowledge test is required to be taken by all CDL applicants. The Iowa CDL test consists of 50 questions. To pass, you must correctly answer at least 40 questions (80%). The general knowledge test covers the contents of the Iowa CDL Manual. All CDL applicants (Class A, B and C) must study the following sections: Driving Safely, Transporting Cargo Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Vehicle Inspection Test, Basic Control Skills Test, Road Test. In addition, the Class A CDL test will include questions based on the Combination Vehicles section. Take this CDL practice test now to prepare for the actual IA general knowledge test! To get your CDL, you must pass both the knowledge and skills tests. CDL knowledge tests include: General Knowledge, Passenger Transport, Air Brakes, Combination Vehicles, Hazardous Materials, Tanker Vehicles, Doubles/Triples, School Bus, Firefighter. Depending on what class of license (A, B or C) and endorsements you need, you must take one or more knowledge tests. A special endorsement is also required to drive certain types of vehicles. The following endorsements may be used with a Class A, B or C CDL: HazMat (H), Tank Vehicles (N), Tank Vehicles Transporting Hazardous Materials (X) and Passenger Transport (P). The School Bus endorsement (S) is only available for Class A or B CDL, and the Doubles/Triples endorsement (T) is only available for Class A driver's licenses.
1. When checking tires, which of the following is not a problem?
Cracked valve stems
Too much air pressure
4/32 inch tread depth on front tires
2. While driving at night, use __________ when it is safe and legal to do so.
interior lights
high beams
low beams
3. When approaching a vehicle as part of a pre-trip inspection, which of the following could be a sign of trouble?
Inflated tires
Fresh oil under the vehicle
Parking brake is on
4. When only the tractor has ABS:
you should be able to maintain steering control during braking.
there is a greater chance of jackknifing.
the trailer is less likely to swing out.
5. When driving in heavy traffic, the safest speed is:
5 mph below the posted speed limit.
the speed of other vehicles, up to the posted limit.
the posted speed limit.
6. What is the minimum number of tie-downs for a 20 foot load?
1
2
3
7. Which of the following vehicles is most likely to turn over?
3 axle tractor semitrailer
65 ft. conventional double
Triple trailer
8. Before starting down a hill, you should slow down and shift down:
to a speed that you can control without using the brakes hard.
so you can coast downhill.
to a gear that will cause your engine to exceed its redline.
9. Driving in very hot weather:
can decrease oil pressure.
should never be done.
can increase tire pressure.
10. The height of a vehicle's center of gravity is important for safe handling. Why?
A high center of gravity means you are less likely to tip over.
Trucks with a high center of gravity have better traction.
Trucks with a high center of gravity can roll over at the posted speed limit for a curve.
 
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Frequently Asked Questions

If you are under 18, you must follow the Iowa Graduated Driver Licensing (GDL) Program. Here are the three phases of the program and the corresponding ages:

  1. Instruction permit? you must be 14 years old. After holding the permit for six months without traffic violation, you can also apply for a minor school license at 14 ½ years old. This special permit is optional and allows you to drive to school or to school activities within a 50-mile distance from your home.
  2. Intermediate license ? you must be 16 years old and have held an instruction permit for 12 months.
  3. Full license ? you must be at least 17 and have held an intermediate license for 12 months. Alternatively, you can directly obtain a class C driver's license at 18.
You have two options:

  1. You can schedule an appointment to take the exam at a service center. Simply locate the nearest Iowa DMV branch and choose your preferred date and time.
  2. If you are a minor between 14 and 17, you can take the knowledge test at a participating school/agency or at home using an electronic device connected to the internet. Once your parent completes and submits the application to Proctor Knowledge Exam Form, you’ll receive an email with instructions for proceeding. After successfully passing the exam, make an appointment to obtain the permit.

You can schedule an appointment for either option on the Iowa Department of Transportation website.

When applying for a driver’s license for the first time, you must bring the following documents:

  • Proof of identity, date of birth, and lawful status (e.g, U.S. passport, birth certificate, certificate of naturalization). If your legal name differs from your identity document, provide proof of the change, such as a certified marriage certificate, court order documents, or ID card.
  • Proof of Social Security Number (SSN).
  • Two proofs of Iowa residency and current residential address (e.g, Iowa voter registration card, utility bill, credit card statement…). If you are under 18 and unmarried, your parent/guardian must sign the Written Consent form to establish your residence. Additionally, provide a second printed document displaying your current name and current Iowa residential address, such as a report card or medical form.

You can use the online checklist provided by the Iowa DOT to ensure you have all the required documents. 

The DMV written test in Iowa is not exclusively provided in English but is offered in various languages, including Albanian, Arabic, Bosnian, Burmese, Cambodian, Chinese, French, German, Greek, Hebrew, Hmong, Italian, Korean, Laotian, Polish, Portuguese, Russian, Somali, Spanish, and Vietnamese. If you need an interpreter for a language not provided, you have to schedule an appointment.
To get ready for the DMV written test, start by reading the Iowa Driver License Manual. This manual has all the info you need to study for the exam: traffic signs, road rules, and safe driving practices. Then, check what you've learned with our free practice tests!

For new drivers in Iowa, various restrictions apply:

Instruction Permit
  • You cannot drive alone and you must be accompanied by a driver education instructor, a licensed parent/guardian, a licensed member of your family who is at least 21, or a licensed adult who is at least 25 (with parental permission if you are a minor).

Minor School License
  • You can't drive alone, except for school activities between 5 a.m. and 10 p.m.

Intermediate License
  • You cannot drive alone between 12:30 a.m. and 5 a.m., unless a parent/guardian completes a Waiver of Intermediate Driver’s License Hour Restriction form.
  • For the first six months, you cannot transport more than one minor without supervision, except for siblings.

The instruction permit is valid for four years. During this period, complete the 20 hours of supervised driving and after holding the permit for 12 months and maintaining a clean driving record for 6 months, you can apply for the intermediate license.
If you fail your DMV written test in Iowa, you have to wait at least one business day before retaking it. Before trying again, focus on the sections of the manual you have overlooked and consider signing up for DMV Premium to access additional practice tests!

IA CDL Practice Test

Number of questions: 50
Correct answers to pass:40
Passing score:80%
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