How to Pass the CDL Test: A 7-Day Permit Plan

What should I study for the CDL permit test?

Your own state's CDL manual: sections 1 to 3 for General Knowledge, section 5 for Air Brakes and section 6 for Combination Vehicles, plus the endorsement sections you need.

Every state's manual is built on the same national model, so the content is almost identical, but use your own state's version for its fees, rules and any local differences. The manual is free from your licensing agency's website.

Read each section once, slowly, then stop reading and start answering questions. Rereading feels productive but teaches little; answering, getting it wrong and reading the explanation is what makes rules stick.

Which manual sections each test draws on
Test	Manual sections	Questions (Washington)
General Knowledge	1 to 3: introduction, driving safely, transporting cargo	50
Air Brakes	5: air brakes	25
Combination Vehicles	6: combination vehicles	20

How do I study for the CDL test in a week?

Day 1, a full practice test; days 2 to 5, the numbers and then one test each with its manual section and drill; day 6, a second full practice test; day 7, only your misses.

Our plan, about 45 minutes a day

Day 1
95 min
Take the full [CDL practice test](/cdl-practice-test). Note which part is furthest below 80%.
Day 2
45 min
Learn the numbers table on this page. Write each on a card with the condition that goes with it.
Day 3
45 min
Air Brakes: reread section 5, then the [Air Brakes drill](/cdl-air-brakes-test). Redo every miss.
Day 4
45 min
Combination: reread section 6, then the [Combination drill](/cdl-combination-test). Say the coupling steps out loud in order.
Day 5
45 min
General Knowledge: inspection, skids and emergencies, then the [General Knowledge drill](/cdl-general-knowledge-test).
Day 6
95 min
A second full practice test on new questions. Every part should clear 80%.
Day 7
30 min
Only your misses and your number cards. Then book the test.

If the first practice test shows one part far behind, move its day to the front. The plan is a default, and the weakest part is where a day buys the most points. Class B drivers can drop day 4 and give it to whichever test scored lowest.

Follow the plan with the right questions

Eight full mocks and four drills for each knowledge test, every answer explained from the manual.

The CDL Pass Pack gives you 8 full mocks on the real clock, 12 drills of 12 questions for the sections that cost you points, and a predictor that turns your mocks into the odds of reaching your target. One payment, no subscription, and your free score stays free.

Prep courses for these tests usually cost $19 to $129. The CDL Pass Pack is US$39 (£29), once.

See the CDL Pass Pack How our questions are built and checked

8
timed mocks: 12
topic drills: 1
score predictor

Which numbers do I need to memorize?

The same rules with numbers come up again and again: learn the table below so you can say each number and the condition it belongs to.

The numbers to know, with where each comes from
Rule	Number	Source
Following distance	1 second per 10 feet of vehicle length below 40 mph; add 1 second above 40 mph	State CDL manual
Stopping at 55 mph (dry)	About 142 ft perception + 61 ft reaction + 216 ft braking = 419 ft; air brakes add about 32 ft of lag	State CDL manual
Tread depth	At least 4/32 inch on front (steering) tires, 2/32 inch on all others	49 CFR 393.75
Warning triangles, two-way road	Within 10 ft of the vehicle, then about 100 ft behind and 100 ft ahead	State CDL manual
Warning triangles, divided or one-way road	10 ft, 100 ft and 200 ft behind, toward approaching traffic	State CDL manual
Cargo checks	Within the first 50 miles, then every 3 hours or 150 miles, whichever comes first	State CDL manual
Alcohol	None within 4 hours of duty; 0.04 is DUI in a CMV; any detectable amount means 24 hours out of service	49 CFR 392.5; state CDL manual
Governor	Cut-out about 125 psi, cut-in about 100 psi	State CDL manual, air brakes
Low-air warning	Must come on before pressure falls below 60 psi	State CDL manual, air brakes
Spring brakes / tractor protection valve	Come on, or close, between 20 and 45 psi	State CDL manual, air brakes and combinations
Air build-up (dual system)	85 to 100 psi within 45 seconds	State CDL manual, air brakes
Leakage, engine off	Released: under 2 psi a minute (single), 3 (combination). Applied: under 3 (single), 4 (combination)	State CDL manual, air brakes
Slack adjuster free play	No more than about 1 inch when pulled by hand	State CDL manual, air brakes

A good way to drill them: cover the middle column, read the rule, say the number aloud, and uncover. Then do it the other way round, from number to rule, because the test often gives you the number and asks what it means.

How should I work a CDL question?

Name the rule the question is testing, recall its number or condition, then check each option against it; most wrong options are right for a different condition.

CDL-style question 1 · Following distance
You are driving a 70-foot combination at 50 mph on a dry road. By the CDL manual's rule, at least how many seconds should you leave between you and the vehicle ahead?
1. A7 seconds
2. B8 seconds
3. C5 seconds
4. D10 seconds
Worked answer
B: 8 seconds. One second for each 10 feet of length is 7 seconds, and you add 1 second because you are above 40 mph: 8 seconds.
1. Length: 70 ÷ 10 = 7 seconds.
2. Speed is over 40 mph, so add 1 second.
3. 7 + 1 = 8 seconds.
The trap: Stopping at 7. The extra second above 40 mph is the part of the rule people forget.
CDL-style question 2 · Mountain driving
Your safe speed on a long downgrade is 45 mph and you are in the right gear. How should you use the brakes?
1. ALight, steady pressure all the way down
2. BBrake firmly to 40 mph, release, and repeat when you reach 45 mph
3. CBrake to 25 mph, then coast in neutral
4. DFan the pedal quickly every few seconds
Worked answer
B: Brake firmly to 40 mph, release, and repeat when you reach 45 mph. Snub braking: brake hard enough to feel a definite slowdown until you are 5 mph below your safe speed, release, and repeat when you are back at the safe speed.
1. Pick the safe speed: 45 mph.
2. Brake until 5 mph below it: 40 mph.
3. Release, let it climb back to 45, and repeat.
The trap: Light, steady braking feels gentle but heats the drums continuously, which causes brake fade.
CDL-style question 3 · Coupling
After coupling, you look at the fifth wheel. Which of these shows the coupling is right?
1. AThe jaws are closed around the head of the kingpin
2. BThere is a small gap between the upper and lower fifth wheel
3. CNo gap between the fifth wheels, the jaws closed around the shank of the kingpin, and the release arm locked
4. DThe release arm is in the open position
Show the worked answer
C: No gap between the fifth wheels, the jaws closed around the shank of the kingpin, and the release arm locked. The upper and lower fifth wheel should touch with no gap, the jaws should close around the shank (not the head) of the kingpin, and the locking lever should be in the locked position with the safety latch over it.
1. Look for a gap: there must be none.
2. Check the jaws are around the shank.
3. Check the release arm is locked and latched.
The trap: Accepting a small gap. A gap can mean the kingpin is riding on top of the jaws (a high hitch), and the trailer can come loose.

What should I do on CDL test day?

Bring the documents your state lists, read every question twice, watch for words like "not" and "except", and do not change an answer unless you find a clear reason.

Check your state's list: driver's license, proof of identity and residency, Social Security number, medical certificate or self-certification, and the fee.
Take the test you are least sure of first, while you are fresh, if your office lets you choose.
Read each question twice. Find the condition (single or combination, released or applied, front tire or other) before reading the options.
Eliminate options that belong to a neighboring rule, then choose.
If you fail one test, ask when you can retake it, then go home and drill only that test.

Why do people fail the CDL permit test?

Mostly by skipping the Air Brakes and Combination sections, mixing up similar numbers, and reading too fast; few fail because the material is hard.

Studying General Knowledge for a week and Air Brakes for an evening, then failing the shorter test by one question.
Learning numbers without their conditions, so 3 psi gets used where 4 psi applies.
Answering from car-driving habits: a truck needs far more following distance, and a skid in a tractor-trailer is corrected differently.
Memorizing practice answers rather than rules; the real questions are worded differently.
Booking the DMV after one good practice score instead of two.

Frequently asked questions

Can I pass the CDL test without studying?

Some experienced drivers do, but the 80% line on each test, and the numbers on Air Brakes, catch many people who rely on experience alone.

How long should I study for the CDL permit?

About a week of 45 minutes a day for most people, longer if you are new to trucks and air brakes.

Are online CDL practice tests enough?

They help most when every answer is explained and tied to the manual. Use them with the manual, not instead of it.

Should I take all the tests on one day?

If you are ready for all of them, yes. If one part is still below 80% in practice, take the others and come back for it.

What is the hardest CDL permit test?

Many people find Air Brakes hardest because of its numbers, while General Knowledge is the longest. The CDL test guide compares them.

Get your permit on the first visit

Eight full CDL-style mocks, four drills per test and every answer explained, for one payment.