CDL Study Resources That Match Your State Manual

Last updated: October 17, 2026

Your CDL knowledge test is based on your state’s CDL manual. A lot of practice material isn’t. This page explains why that matters, gives you three ten-minute checks you can run on any practice source (ours included), and lists the options as honestly as I can.

The mismatch problem

Most practice questions online come from generic pools. They are written once for a national audience and reused for every state. Your test doesn’t work that way. Your state’s licensing agency publishes its own manual, and the knowledge test is drawn from that manual. States use different editions of the model manual, add sections of their own, and word things differently. (Our Sources page shows the edition each state lists.)

The gap matters most on three tests: General Knowledge, Combination Vehicles and Air Brakes. They are separate knowledge tests, each taken on its own, and they are where many candidates tend to get stuck. A question that is right for the national model manual can be slightly off for your state’s edition, and you won’t know unless you check.

How to check any practice source against your state manual

You need your state’s current CDL manual (a free PDF from your licensing agency) and about ten minutes per check. These work on any app, website or book.

Check 1: The numbers check (10 minutes)

1. Pick 10 practice questions whose answers are numbers: a following distance, a tread depth, a stopping distance, a speed reduction, a distance in feet, a pressure.
2. For each one, search your manual’s PDF for the topic (use Find, or Ctrl+F / Cmd+F) and read the passage.
3. Compare the number in the manual with the number in the practice answer.
4. If all 10 match, that is a good sign. If any don’t, write down which ones. It could be a different edition or it could be a mistake. Either way, go with your manual.

Numbers are the fastest thing to verify because they either match or they don’t.

Check 2: The edition check (10 minutes)

1. Find your manual’s edition. Look on the cover and in the page footers; many say “AAMVA Version” followed by a month and year.
2. Find out which manual the practice source says it was written from. A good source names the edition or links to the manual.
3. If it only says something like “updated for 2026” and can’t say which state or which edition, treat it as a generic pool.
4. Download one other state’s manual and compare the two tables of contents. Pick two sections that are worded differently or exist in only one of them, then see whether the practice source has questions on your state’s version.

Check 3: The show-your-work check (10 minutes)

1. Take 3 questions each from General Knowledge, Combination Vehicles and Air Brakes, nine in all.
2. Read the explanation for each. Does it point to a manual section or a regulation (a 49 CFR part, for example), or does it only restate the answer?
3. Look up what it points to, and check that the source says what the explanation says it does.
4. If the explanations never point anywhere, you can’t verify the source, and neither can anyone else.

What to do with the results. If a source passes all three checks, it is a reasonable supplement to your manual. If it fails any of them, treat it as practice only and learn the facts from your manual.

Official sources

The manual is the authority. Our Sources page lists every state’s official CDL manual with the edition each state shows, the federal regulations the questions cite, and the state-law pages behind several state question sets. It also says, state by state, how many of our questions were checked against that state’s manual. I keep all the links in one place instead of repeating them here.

Open the Sources page

CDL Permit Pass Pro’s questions are written from the official state manuals and FMCSA regulations — sources listed so you can check.

12 sample questions

These are 12 questions from the General Knowledge section of CDL Permit Pass Pro, with the correct answer and the app’s one-line explanation for each. Use them for Check 1: look each fact up in your own manual and see whether your edition agrees. They are practice questions, not official test questions.

1. How much tread must a steering-axle tire have, at a minimum, in each major groove?
   Answer: 4/32 of an inch.
   Why: Front tires on the steering axle are held to a stricter limit than the others: each major groove needs 4/32 inch of tread or more.
2. How many reflective warning triangles must most commercial vehicles carry?
   Answer: Three.
   Why: Federal rules call for three bidirectional reflective triangles.
3. How often should you check tire pressure and temperature on a hot day?
   Answer: Every 2 hours or 100 miles.
   Why: In hot weather, inspect tires every two hours or 100 miles; air pressure rises with heat.
4. Total stopping distance is made up of which three parts?
   Answer: Perception, reaction, and braking distance.
   Why: Stopping takes three stages added together: the distance covered while you recognize the hazard, while your foot moves to the brake, and while the brakes slow the vehicle.
5. If you double your speed, about how much longer does it take to stop?
   Answer: About four times the distance.
   Why: Whenever you double your speed, it takes about four times as much distance to stop, and impact force is four times greater.
6. How much should you reduce speed on a wet road?
   Answer: About one-third.
   Why: On a wet road, cut your speed by roughly a third; 55 mph would become about 35 mph.
7. At what speed can hydroplaning occur?
   Answer: As low as 30 mph.
   Why: With enough standing water, tires can lose contact with the road at only about 30 mph.
8. What are escape ramps used for?
   Answer: Stopping runaway vehicles safely.
   Why: These ramps use deep loose gravel or an uphill grade to bring a runaway truck to a stop without hurting the driver.
9. A 40-foot vehicle traveling over 40 mph should keep how much following distance?
   Answer: 5 seconds.
   Why: Use 1 second per 10 feet (4 seconds for 40 feet) and add 1 second for speeds over 40 mph, for 5 seconds.
10. When should you dim your high beams for oncoming traffic?
    Answer: Once it is within 500 feet.
    Why: Switch to low beams when an oncoming vehicle is closer than 500 feet, and do the same when you are less than 500 feet behind someone.
11. What field of vision must a CDL driver have?
    Answer: At least 70 degrees in each eye.
    Why: 49 CFR 391.41 requires a field of vision of at least 70 degrees in the horizontal meridian in each eye.
12. Which class of fire involves flammable liquids like gasoline?
    Answer: Class B.
    Why: Class B fires involve flammable liquids such as gasoline, oil, and grease.

Your options, honestly

Use all of these with the three checks above, including mine. Details for products other than mine come from their own websites and App Store listings as of October 17, 2026. They are the providers’ own descriptions, and I have not tested them.

CDL Permit Pass Pro on Google Play

A note from the builder

I’m an inventory accountant, not a truck driver or a CDL instructor. I built CDL Permit Pass Pro from the state manuals because the mismatch annoyed me: the practice questions I kept finding didn’t say where they came from, and I couldn’t check them. So I put the sources on a page where anyone can check them. This page is free whether or not anyone buys the app.

If you find a question that disagrees with your state’s manual, email me at geteagapps@gmail.com and I will check it against the manual.

— Edwin, Get EAG Apps