Free, full Iowa CDL general knowledge test practice right here in your browser — real exam format (50 questions, 80% to pass), diagnostic and adaptive modes, spaced-repetition review, and a readiness dashboard. No signup, no paywall — your progress is saved automatically on this device. Matched to the official Iowa DOT knowledge exam.
CDL safety scenario 73: Why must cargo weight be balanced side to side?
D. Uneven weight can make the vehicle lean or roll over more easily — Uneven weight can make the vehicle lean or roll over more easily. Commercial drivers are expected to manage this situation before it becomes a crash risk. The CDL manual emphasizes controlling the vehicle, inspecting safety-critical systems, and correcting hazards promptly.
After coupling, when you test the connection by pulling forward, you should:
D. Pull firmly to ensure the kingpin doesn't pop out — After coupling, pull the tractor firmly forward (with trailer brakes locked) to confirm the fifth wheel jaws have closed around the kingpin.
If your vehicle catches fire, the first thing you should do is:
D. Pull off the road, shut off the engine, and get away from the vehicle — Pull over safely, shut off the engine, grab your fire extinguisher if safe to use, and get away from the vehicle. Call 911.
When you back a combination vehicle, you should:
B. Back slowly, use a helper if available, and look at your target through the driver-side mirror — When backing a combination vehicle: use the lowest reverse gear, use both mirrors, back to the driver's side whenever possible so you can see your target, and use a helper (spotter) to guide you.
What is an ELD (Electronic Logging Device), and when is it required?
B. An electronic device that automatically records duty status based on engine data, required for most CMV drivers who must keep RODS — An ELD automatically records driving time and duty status using engine data. Since the ELD mandate (49 CFR Part 395), most CMV drivers who are required to keep records of duty status must use an ELD.
To test that the parking brake holds, you should:
C. With the parking brake set, gently pull forward against it in a low gear — Gently pulling against the set parking brake in a low gear confirms it can hold the vehicle before you rely on it.
After a HOS violation is discovered at a weigh station, what can happen to the driver?
B. The driver may be placed out of service at the roadside until enough off-duty time has passed to bring hours into compliance — An HOS violation can result in the driver being placed out of service at the roadside until enough off-duty time has accumulated to comply with the hours-of-service regulations.
During the pre-trip inspection, a driver must check the engine oil level when:
A. The engine has been off for at least a few minutes so oil drains to the pan — Oil level should be checked after the engine has been off for a few minutes so all oil drains back to the oil pan. Checking immediately after shutdown gives an artificially low reading.
To avoid distracted driving in a CMV, you should:
D. Set up navigation and complete tasks before you start driving — Handling navigation, food, and paperwork before driving keeps your eyes and attention on the road where they belong.
A converter dolly is used to:
D. Connect a second or third trailer to the combination — A converter dolly is an axle assembly with a fifth wheel that lets you couple an additional trailer behind the first.
The Iowa CDL general knowledge test has 50 questions, and you need 80% to pass — at least 40 correct answers. The practice tests on this page use the same format. The 80% passing score is a federal FMCSA standard used by every state.
80%. You can miss at most 10 of the 50 questions. The readiness dashboard on this page tracks whether you're consistently scoring above that bar.
In Iowa, driver licensing is handled by the Iowa Department of Transportation (Iowa DOT), so you'll often see the exam called the Iowa DOT CDL general knowledge test. The practice tests on this page match the official Iowa DOT knowledge exam format.
Yes. Every practice test on this page and everything in the DMVPrep iPhone app is free — no ads, no paywall, no account.
Federal motor carrier safety regulations (FMCSA) — the same rules every state's CDL exam is drawn from. Every question in the DMVPrep app cites the regulation or handbook section it comes from.
Yes — the DMVPrep app includes all 3,745+ questions in Spanish, and the whole app works in Spanish.