Iowa CDL Class B Practice Test (IA) 3

5 out of 5 (57 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Preparing for the Iowa CDL Class B test in 2026? You've found the right spot. Our third practice test is tailored specifically for Class B CDL applicants, offering a comprehensive preparation experience. This CDL practice test is an essential tool in your arsenal, providing a realistic simulation of the actual DMV written test. With 20 carefully curated permit test questions, the test ensures a broad coverage of crucial topics. These include pre-trip vehicle inspection, basic vehicle control, gear shifting techniques, managing hills and downgrades, effective communication on the road, speed control, and drug and alcohol awareness. Accuracy is key, and with a requirement to correctly answer at least 16 questions, this DMV practice test challenges and educates simultaneously. Our Iowa CDL class B practice test adopts the multiple-choice and true/false format, mirroring the actual written permit test. This familiarizes you with the question style and helps develop skills in identifying the correct answers. The questions you'll encounter are strikingly similar to those in the real general knowledge test, both in content and structure. This similarity is a significant advantage, as it offers a realistic practice environment, boosting your confidence and preparedness. One of the standout features of our 2026 Iowa CDL practice test is the stress-free learning environment it provides. Unlike the actual DMV written test where the pressure is high, our practice test allows you to learn at your own pace, without the fear of failure. This relaxed setting is conducive to effective learning, ensuring that you absorb and retain information better. Remember, the set of questions remains the same no matter how many times you attempt the test. This consistency is beneficial as it allows you to track your progress and focus on areas where you need improvement. So, whether you're a first-timer or a seasoned applicant, our Iowa CDL Class B practice test is an invaluable resource in your preparation journey in 2026.
FREE CDL Practice Test App
Pass your Iowa CDL General Knowledge test with the NextDoorDriving app. Real questions and answers—100% free and ad-free.
Download on the App Store

Sample Iowa CDL Test Questions - General Knowledge

Question 1

If no qualified responder is already caring for an injured person, which actions follow CDL accident-scene guidance?

  1. A Move a severely injured person only when fire or passing traffic creates danger
  2. B Control heavy bleeding by applying direct pressure to the wound
  3. C Keep the injured person warm
  4. D All of the above

Correct answer: D – All of the above

The manual lists all three actions as basic assistance at an accident scene. Do not move a severely injured person unless fire or passing traffic makes movement necessary. Apply direct pressure to control heavy bleeding and keep the person warm. If a qualified person is already helping, stay out of the way unless asked to assist.

Source: Iowa Commercial Driver’s License Manual — § 2.20.3, “Care for the Injured”

Question 2

Which feature can help you identify a vehicle equipped with an antilock braking system?

  1. A Every vehicle with a speed retarder has ABS
  2. B The wheels lock during a high-speed brake test
  3. C The vehicle has a yellow ABS malfunction lamp
  4. D The vehicle has an automatic transmission

Correct answer: C – The vehicle has a yellow ABS malfunction lamp

The Iowa CDL manual identifies yellow malfunction lamps as an indication that a vehicle has ABS. Tractors, trucks, and buses have the lamp on the instrument panel; trailers generally have it on the left side near a front or rear corner. On newer vehicles, the lamp normally illuminates briefly during the startup bulb check and then goes out.

Source: Iowa Commercial Driver’s License Manual — § 5.1.16, “Antilock Braking Systems (ABS)”

Question 3

What does “off-tracking” describe when a combination vehicle turns?

  1. A Operating the vehicle on an unpaved road
  2. B Passing another vehicle on the right
  3. C Allowing the trailer to sway between lanes
  4. D The rear wheels following a different path from the front wheels

Correct answer: D – The rear wheels following a different path from the front wheels

During a turn, a vehicle’s rear wheels do not follow the same path as its front wheels. This difference is called off-tracking. The rear wheels of a trailer off-track more than those of the powered unit, and longer combinations generally off-track more. Drivers must account for this path when positioning the vehicle through a turn.

Source: Iowa Commercial Driver’s License Manual — § 6.1.6, “Turn Wide”

Question 4

What two broad categories should a commercial driver scan for while looking ahead?

  1. A Traffic and road conditions
  2. B Vehicles and traffic signals only
  3. C Disabled vehicles and roadway debris only
  4. D Curves and potholes only

Correct answer: A – Traffic and road conditions

Commercial drivers should look well ahead and scan both traffic and road conditions. Traffic checks include vehicles entering or leaving the roadway, changing lanes, turning, or slowing. Roadway conditions may require changes in speed or position. Seeing these developments early gives the driver more time to respond smoothly instead of making a sudden maneuver.

Source: Iowa Commercial Driver’s License Manual — § 2.4.1, “Seeing Ahead”

Question 5

If crossing deep standing water cannot be avoided, what should you do to help protect the brakes?

  1. A Maintain gentle brake pressure while crossing
  2. B Apply hard pressure to the brake and accelerator after leaving the water
  3. C Disconnect the steering-axle brakes after crossing
  4. D Reduce engine speed and avoid using the brakes

Correct answer: A – Maintain gentle brake pressure while crossing

When crossing deep water is unavoidable, slow down, select a low gear, and gently apply the brakes. Light pressure holds the linings against the drums or discs and helps keep mud, sand, silt, and water from entering. Continue light pressure briefly after leaving the water to heat and dry the brakes, then test them when it is safe.

Source: Iowa Commercial Driver’s License Manual — § 2.13.2, “Driving”

Question 6

Before going beneath a tractor-trailer to inspect the coupling, why should you shut off the engine and take the key?

  1. A To prevent the key from being misplaced
  2. B To prevent someone from moving the tractor while you are underneath it
  3. C To unlock protected parts of the brake system
  4. D To reduce battery drain during the inspection

Correct answer: B – To prevent someone from moving the tractor while you are underneath it

Before inspecting the coupling from beneath the trailer, secure the tractor by placing the transmission in neutral, applying the parking brakes, shutting off the engine, and taking the key. Keeping the key with you prevents another person from starting or moving the tractor while you are underneath it. This protects the inspector from being struck or crushed by unexpected movement.

Source: Iowa Commercial Driver’s License Manual — § 6.4.1, “Coupling Tractor-Semitrailers”

More Iowa CDL Practice Tests
Other CDL Endorsements