Iowa CDL Practice Test 2025

Iowa CDLs are issued by the Iowa Department of Transportation (Iowa DOT), Motor Vehicle Division — not a DMV. CDL applicants must visit an Iowa DOT driver's license office to take the required knowledge tests, submit a current DOT medical certificate, and complete the CDL skills test. Iowa DOT offices are located throughout the state, with major locations in Des Moines, Cedar Rapids, Davenport, Sioux City, and Waterloo.

All Iowa CDL applicants must pass the General Knowledge test. Additional tests are required based on the vehicle class and endorsements sought: Combination Vehicles (Class A), Air Brakes (if the vehicle has air brakes), Passenger Transport, Hazardous Materials (plus TSA security threat assessment), Tank Vehicles, Doubles/Triples, and School Bus. Each test requires a minimum score of 80%. Iowa CDL applicants should understand the state's seasonal overweight permit system as part of their CDL operational knowledge.

The FMCSA OWI BAC limit of 0.04% applies to CDL drivers operating a CMV in Iowa. Iowa uses OWI (Operating While Intoxicated) terminology. Iowa also prohibits CDL drivers from consuming alcohol within 4 hours before operating a CMV. A CDL driver who tests at 0.04% BAC or above is immediately placed out of service and faces CDL disqualification. Iowa's true zero-tolerance standard of 0.00% applies to CDL holders under 21 even when operating a non-CMV personal vehicle.

Iowa Code § 321.463 authorizes Iowa DOT to issue seasonal overweight permits allowing grain and livestock haulers to operate above standard legal weight limits during designated agricultural seasons on designated routes. CDL drivers hauling grain, corn, soybeans, or livestock during these seasons must obtain the appropriate permit, carry it in the vehicle, and comply with all route and timing restrictions. These permits are distinct from standard oversize/overweight special permits used for non-agricultural loads. Violating permit conditions can result in fines and CDL disqualification.

RAGBRAI (Register's Annual Great Bicycle Race Across Iowa) is held each July and draws tens of thousands of participants cycling across the state over approximately one week. Along the route, local authorities temporarily close or restrict roads to commercial vehicle traffic. CDL dispatchers and drivers must monitor Iowa DOT and local authority announcements for RAGBRAI closures and plan alternate routes during the event. Iowa DOT typically publishes RAGBRAI-related commercial vehicle routing information in advance of the event each year.

A Class A CDL allows you to operate any combination of vehicles with a Gross Vehicle Weight Rating (GVWR) of 26,001 lbs or more, provided the towed unit exceeds 10,000 lbs — this includes tractor-trailers and double/triple trailer rigs. A Class B CDL covers single vehicles with a GVWR of 26,001 lbs or more, or any such vehicle towing a unit not exceeding 10,000 lbs — this includes straight trucks and large buses. A Class C CDL is required for vehicles designed to carry 16 or more passengers (including the driver) or for vehicles transporting hazardous materials that require placarding, when those vehicles do not qualify for Class A or B.

CDL fees vary by state and by the class and endorsements you obtain. Most states charge separate fees for the CDL knowledge test ($10–$30 per attempt), the CDL skills test ($50–$150), and the CDL license itself ($50–$100). Additional fees apply for each endorsement (HazMat, Tanker, Passenger, etc.). The HazMat endorsement also requires a TSA security threat assessment fee of approximately $86. Check your Iowa DMV website for current fee schedules.

Federal regulations (49 CFR 383.133) require that CDL applicants be able to read and speak the English language sufficiently to understand highway traffic signs and signals and to respond to official inquiries. Many states offer CDL knowledge tests in Spanish and other languages for non-commercial knowledge questions, but the actual CDL test must be taken in a language that allows the driver to meet the English proficiency requirement. Check with the Iowa DMV for available language options.

In most states, a CDL is valid for 4–8 years (commonly 4–5 years). To renew your Iowa CDL, you typically need to visit a DMV office, pass a vision test, pay the renewal fee, and update your medical certification (DOT physical). If you hold a HazMat endorsement, your TSA background check must also be current. CDLs cannot generally be renewed online due to federal requirements for in-person verification of medical certification.

If you fail the CDL General Knowledge test in Iowa, you are typically required to wait a specified period (commonly 1–7 days) before retaking it. Most states allow 2–3 attempts before requiring additional waiting periods or study requirements. There is usually a retest fee for each attempt. Focus on the areas you missed — most states provide a score sheet showing which topic areas you need to review.