If you’re getting ready to head to the DMV for your CDL permit, one of the first things you want to know is exactly what you’re walking into. How many questions are on the test?
This guide breaks down every section of the exam, the exact number of questions per section, the passing score you need, and what each section actually covers so there are zero surprises on test day.
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The CDL Permit Test Breakdown
Here’s the first thing a lot of new applicants don’t realize: the CDL permit test isn’t a single exam. It’s a series of knowledge tests, and the specific tests you take depend on which CDL class you’re applying for and which endorsements you need.
Every applicant takes the General Knowledge test. From there, additional tests are required based on your goals:
- Applying for a Class A CDL: You’ll also take Air Brakes and Combination Vehicles which is 95 questions total across three tests.
- Applying for a Class B CDL: You’ll take General Knowledge and Air Brakes which is 75 questions total.
- Adding endorsements (Hazmat, Tanker, Passenger, Doubles/Triples, School Bus) Each endorsement has its own separate knowledge test on top of the above.
The passing score for every single section is 80%. You must score 80% or higher on each test individually and a high score on one section doesn’t offset a low score on another.
| What it covers | # of Questions | CDL A Permit | CDL B Permit | |
|---|---|---|---|---|
| General Knowledge | Basic trucking concepts, safe driving & CDL regulations | 50 | ✔️ | ✔️ |
| Combination | Covers driving vehicles with a tractor-trailer combination | 20 | ✔️ | ❌ |
| Air Brakes | Focuses on vehicles equipped with air brakes | 25 | ✔️ | ✔️ |
CDL Permit Test Questions by Section
General Knowledge: Required for All CDL Classes
- Questions: 50
- Correct Answers Needed: 40
- Passing Score: 80%
- Time Limit: 60 min
- Vehicle inspection procedures (pre-trip checks, what to look for)
- Basic vehicle control (shifting, backing, turning, managing speed)
- Shifting and backing maneuvers
- Coupling and uncoupling (more detail in Combination Vehicles)
- Safe driving practices (space management, following distance, night driving, adverse weather)
- Transporting cargo safely (securing loads, weight limits, center of gravity)
- Hazardous materials basics (when placards are required, general handling)
- Accident procedures and emergency response
- Hours of service regulations (how long you can drive, rest requirements)
- Vehicle systems and how they work
Air Brakes: Required for Class A and Class B (and Anyone Driving Air Brake Vehicles)
- Questions: 25
- Correct Answers Needed: 20
- Passing Score: 80%
- Time Limit: 30 min
- Components of the air brake system (compressor, reservoirs, valves, brake chambers, slack adjusters)
- How air brakes work differently from hydraulic brakes (brake lag, stopping distances)
- Pre-trip air brake inspection procedures (the pressure build test, air loss rate, low pressure warning, spring brake check)
- Dual air brake systems and how to check them
- Proper use of brakes on downgrades (not riding the brakes, fanning)
- Emergency brake systems and parking brakes
- PSI thresholds you must know:
- Governor cuts out at: 120–125 PSI
- Governor cuts in at: 100 PSI
- Low pressure warning activates at: 60 PSI
- Spring brakes pop out at: 20–45 PSI (varies by vehicle)
- Maximum air loss rate: 3 PSI per minute (single vehicle), 4 PSI per minute (combination)
Combination Vehicles: Required for Class A CDL
- Questions: 20
- Correct Answers Needed: 16
- Passing Score: 80%
- Time Limit: 30 min
- Coupling and uncoupling procedures (fifth wheel, kingpin, landing gear, trailer brakes)
- Inspecting combination vehicles before a trip
- Anti-lock braking systems (ABS) on combination vehicles
- Rollover risks (why combination vehicles are more susceptible and how to prevent them)
- Off-tracking (why the rear wheels of a trailer don’t follow the same path as the front wheels)
- Rearward amplification (crack-the-whip effect) and how speed affects it
- Doubles and triples towing rules (if applicable to your setup)
- Trailer brake systems and how to test them
Hazardous Materials (HazMat): Required for H Endorsement
- Questions: 20
- Correct Answers Needed: 16
- Passing Score: 80%
- Time Limit: 30 min
The HazMat section is one of the longer and more detailed endorsement tests. It’s required for anyone who wants to transport hazardous materials that require placards under federal law.
Important: For HazMat, you must also pass a TSA background check and complete ELDT theory training before you can take this test. The background check can take several weeks, so plan ahead if H endorsement is part of your goal.
What it covers:
- The nine classes of hazardous materials and how to identify them
- Placarding requirements (when placards are required, which placard for which material)
- Shipping papers (what they must contain, where they must be kept)
- Markings and labels (how they differ from placards and when each is required)
- Loading and unloading hazardous cargo safely
- Segregation rules (which materials can’t be loaded together)
- Bulk packaging vs. non-bulk packaging
- Emergency response procedures (spills, leaks, fires)
- Route restrictions for HazMat loads (tunnels, bridges, populated areas)
- Attendance requirements when parked with a HazMat load
Study tip: The HazMat section has a lot of detail around the nine hazard classes and their specific rules. Make a reference card for each class (explosives, gases, flammables, oxidizers, poisons, radioactive, corrosives, miscellaneous) with the key restrictions for each. The exam will test scenario-based judgment, not just definitions.
Tanker Vehicles: Required for N Endorsement
- Questions: 20
- Correct Answers Needed: 16
- Passing Score: 80%
- Time Limit: 30 min
- Liquid surge and how it affects vehicle handling (front-to-back surge, side-to-side surge)
- Baffled vs. unbaffled tanks: the difference and how each affects driving
- Outage (why tanks can’t be completely filled and what rules govern fill levels)
- High center of gravity: why tankers roll over more easily and how to compensate
- Inspecting tank vehicles before a trip (checking for leaks, dome covers, valves)
- Safe driving techniques specific to tankers (smooth acceleration, wide turns, early braking)
- Retest and certification requirements for tank vehicles
Doubles and Triples: Required for T Endorsement
- Questions: 20
- Correct Answers Needed: 16
- Passing Score: 80%
- Time Limit: 30 min
- Coupling and uncoupling double and triple trailer combinations
- Converter dolly: what it is, how it works, and how to inspect it
- Securing the converter dolly when uncoupled
- The crack-the-whip effect and rearward amplification (how it increases with each additional trailer)
- Proper trailer positioning (heaviest trailer immediately behind the cab)
- Safe driving practices for longer combinations (more following distance, wider turns, earlier braking)
- State-specific rules (not all states allow triples)
Passenger Transport: Required for P Endorsement
- Questions: 20
- Correct Answers Needed: 16
- Passing Score: 80%
- Time Limit: 30 min
- Loading and unloading passengers safely (especially at stops and intersections)
- Standing passengers: where they’re allowed, overhead clearance rules
- Emergency exits: location requirements, how to operate them, when to use them
- Prohibited items on passenger vehicles (hazardous materials, certain cargo)
- Handling disruptive passengers
- Mirror usage and pre-trip inspection for passenger vehicles
- Railroad crossing rules specific to passenger vehicles (must stop, not just slow down)
- Charter vs. transit bus distinctions
School Bus: Required for S Endorsement
- Questions: 20
- Correct Answers Needed: 16
- Passing Score: 80%
- Time Limit: 30 min
The School Bus endorsement is required on top of the Passenger endorsement for anyone who wants to drive a school bus. You must already qualify for the P endorsement before adding the S endorsement. You can get the P & S endorsement at the same time.
What it covers:
- Loading and unloading students: the most safety-critical procedures on a school bus
- Danger zone: the area around the bus where students are at highest risk
- Use of mirrors (8-mirror system used on modern school buses)
- Emergency exit procedures and emergency drills
- Railroad crossing procedures for school buses (always stop — no exceptions)
- Specific rules around school bus stop signs and flashing lights
- Student management and behavior procedures
Pre-trip inspection specific to school buses
Study tip: The danger zone and mirror system are the two most tested topics in the school bus section. Know the danger zone distances in all directions around the bus and understand which mirror covers which zone.
Full Summary: CDL Permit Test Questions at a Glance
These question counts reflect New Jersey’s CDL permit testing structure. Many states use very similar totals for the main CDL knowledge tests, but some states may use different question counts, passing scores, or test formats.
| Test Section | Questions | Need to Pass | Score Required | Who Takes It |
|---|---|---|---|---|
| General Knowledge | 50 | 40 | 80% | Everyone |
| Air Brakes | 25 | 20 | 80% | Class A, Class B, any air brake vehicle driver |
| Combination Vehicles | 20 | 16 | 80% | Class A applicants |
| Hazardous Materials (H) | 30 | 24 | 80% | HazMat endorsement seekers |
| Tanker Vehicles (N) | 20 | 16 | 80% | Tanker endorsement seekers |
| Doubles and Triples (T) | 20 | 16 | 80% | Doubles/Triples endorsement seekers |
| Passenger Transport (P) | 20 | 16 | 80% | Passenger endorsement seekers |
| School Bus (S) | 20 | 16 | 80% | School Bus endorsement seekers |
Class A total (General Knowledge + Air Brakes + Combination Vehicles): 95 questions, all at 80% passing threshold
Class B total (General Knowledge + Air Brakes): 75 questions, all at 80% passing threshold
What Happens If You Fail a Section?
Failing one section doesn’t mean you failed everything. You only need to retake the specific section you didn’t pass since you don’t lose credit for sections you already passed.
Retake rules vary by state, but here’s what’s typical:
- Some states allow you to retake a failed section after a waiting period which is usually 1 to 7 days
- Some states limit the number of attempts within a set window (for example, three attempts before a mandatory waiting period or additional requirements kick in)
- Check with your specific state DMV for the exact retake policy before your first attempt
At Driving Academy, our permit prep resources are designed to get you through on the first attempt. The less time you spend retaking written tests, the faster you get to training and on the road.
Frequently Asked Questions
It's not difficult if you're prepared. The questions are straightforward and come directly from the CDL Manual. Most people who fail do so because they underestimated how specific the questions are, particularly around numbers, PSI levels, and procedural sequences.
