Iowa's CDL manual and DMV CDL Practice Tests

for all endorsements

Iowa's CDL Manual

Commercial Driver Handbook

CDL Classes in Iowa The first step is to pick which CDL class to get. Now, in Iowa, there are 3 CDL classes, namely:

  • Class A
  • Class B
  • Class C

Before we define each class, there are two things you need to know — the GVWR and the GCWR.

  • GVWR or Gross Vehicle Weight Rating – the weight of a vehicle (including its load) as stated by its manufacturer.
  • GCWR or Gross Combination Weight Rating – the sum of the GVWR of the vehicle (with the main power unit) and the loaded weight of the towed vehicle/s.

You’ll see why these are important when we explain what each CDL class can operate.

CDL Endorsements in Iowa On top of the CDL classes, there are endorsements that further classify the commercial vehicle you can drive. These endorsements are added to your CDL class. In Iowa, there are 5 endorsements you can get:

  • Double/Triple Endorsement – allows commercial drivers to operate double or triple trailers. To get this, you need to pass a Double and Triple Trailers written exam.
  • Hazardous Material – allows you to transport hazardous materials that require placarding. To get this endorsement, you need to pass the CDL Hazardous Material exam and go through a TSA background check.
  • Passenger – allows you to operate commercial vehicles capable of transporting 16 or more persons. You must pass a Passenger knowledge exam to get this endorsement.
  • School Bus – allows you to only operate school buses. To get this endorsement, you need to pass a School Bus knowledge exam and a Passenger knowledge exam.
  • Tank – allows you to operate trucks that carry liquid or gaseous substances. You need to pass a Tanker knowledge exam to get this endorsement to CDL.

Well, here is a list of the basic CDL requirements in Iowa:

  • Be at least 18 years old if you’re driving interstate AND 21 years old if driving across states.
  • Have a regular driver’s license or Real ID
  • Have documents proving your name, date of birth, and Social Security Number.
  • Have proof of US citizenship or legal presence.
  • Have proof of Iowa residency.
  • Do not have a DUI or any reckless driving record.

DMV CDL Practice Tests

General Knowledge

The general knowledge test is the first of several tests that you will have to complete in order to get your CDL. The questions cover general information about commercial vehicles, driving, and vehicle inspections. The test has a total of 50 questions, and requires at least 40 correct answers to pass.

Air Brakes

You must have an Air brake endorsement on your driver's license to drive a vehicle equipped with an air brake system. This test will test your knowledge of the function, parts, and braking distance of air brakes. The test will consist of 25 questions, and at least 20 correct answers are needed to pass.


The combination endorsement allows you to drive a vehicle with a power unit and one trailer. This test will cover the "ins and outs" of operating articulated vehicles. The exam consists of 25 questions, and requires at least 20 correct to pass.

Hazardous Material

The Hazardous Material endorsement allows the driver to operate a vehicle containing items such as poisons, explosives, flammables, etc. You will also have to pass the TSA Hazardous Material Threat Assessment to get this endorsement. There are 30 questions, 24 correct required to pass.


The Tanker endorsement allows the driver to operate a vehicle weighing more than 26,000 pounds designed to transport any liquid or gaseous material within a tank that is permanently or temporarily attached to the vehicle. There are 20 questions, 16 correct required to pass.

Doubles / Triples

The Doubles/Triples endorsement is required for drivers to pull 2 trailers (doubles) or 3 trailers (triples) connected to a single power unit. There are 20 questions on this test, and 16 correct answers are required to pass.


Bus drivers must have a commercial driver's license with a passenger endorsement in order to operate a vehicle which seats 16 or more, including the driver. There are 20 questions on this test, and 16 correct answers are required to pass.

School Bus

School Bus Endorsement is required for any driver who operates a school bus. After the permit tests the training can be only completed by a local school district. There are 20 questions on this test, and 16 correct answers are required to pass.

Pre Trip Inspection

The Pre-Trip exam is an oral exam where you are expected to check the vehicle parts to insure it is safe for road use. The amount of parts you need to check increase with the size of the vehicle, and by type of vehicle.