Iowa CDL License Requirements:

In order to drive commercial or combination vehicle in Iowa, you need to get the commercial driver’s license (CDL) from Iowa state department of DMV. Commercial vehicles require different CDL class license depending upon the gross weight of the vehicle:

Class A License: To drive a vehicle with Gross Vehicle Weight Rating (GVWR) excess of 26,001 pounds, with towing weighing more than 10,000 pounds, you need to get Class A driver’s license.
Class B License: For vehicles weighing greater than 26,001 pounds with towing less than 10,000 pounds, you must have Iowa CDL class B driver’s license.
Class C License: Vehicles weighing less than 26,001 pounds require class C license. A person with class C license can drive school bus and carry hazardous materials with a vehicle by passing the corresponding endorsement tests.

In order to apply for Iowa CDL license, you must be at least 18 years of age with good physical health and vision. The medical certificate will be issued by DOT. In order to drive the vehicles within two sates you need to be at least 21 years of age. Transportation of hazardous material is directly monitored by USDOT. So background check will be required before starting your driving career in transportation of dangerous materials.

To drive the vehicles with Air brakes, you need to pass the CDL Air Brakes test. Same is the case for School bus, hazardous materials, double/triple, tanker vehicles and so on. After passing the written tests for your desired license category, you will be asked to perform road skills tests.

Iowa CDL Road Skills Tests:

Pre-trip Inspection:

Pre-trip inspection test is done before starting your journey to see if everything is right in the vehicle. You will have to tell the examiner how and why you have done the inspections.

Basic control test:

You will be asked to move the vehicle in a specified area and will be asked to perform certain control tests, if you have gripped on the basic vehicle control.

On-road driving:

This is really the part where you to show your real skills by driving the vehicle on actual road and busy traffic. The examiner will judge your driving abilities in this test and confirms that whether you're ready to take your vehicle on the road.
Remember, road skills tests will be done in the same vehicle class for which you are trying to obtain the license.

Useful Links:

Iowa CDL Practice Tests