commercial driver's license
CDL (상업용 운전면허)A commercial driver's license (CDL) is required to drive a commercial motor vehicle (CMV).
It comes in Class A, B, or C. Endorsements add what you may haul or drive; restrictions take things away. You may hold only one driver's license, and violations in your own car can still take your CDL away.
Differs by state: Who needs a CDL follows the federal definition everywhere, but California and Texas run their own class schemes. Six states (California, Texas, Maine, Maryland, Oregon, Wyoming) also use the letters A, B and C for ordinary non-commercial licenses. So 'Class A' alone does not always mean a CDL; look for the word commercial.
Does not mean: A CDL is not a heavier car license: it is federally standardized, and a CDL holder may not keep a second driver's license.
Example: A moving-company driver is promoted to a heavy straight truck, so she must earn a Class B CDL before driving it.
Also called: CDL, commercial driver license
commercial learner's permit
연습 허가증A commercial learner's permit (CLP) lets you practice driving a CMV under supervision.
You get it by passing the knowledge tests. It is only valid with your regular license, and you must hold it for a minimum time before the skills test. A CLP can carry only the P, S, and N endorsements, with no passengers or cargo in the tank.
Differs by state: Federal law caps a CLP at one year from first issue (49 CFR 383.25(c)). Most states issue it for 180 days and renew it once. Montana, Nebraska, Rhode Island, Wyoming, Indiana, South Carolina and Vermont issue a full year up front, and Rhode Island and Vermont do not renew it. California's and Texas's '1 year' is the renewal cap, not the issued term. The 14-day hold before the skills test is federal (49 CFR 383.25(e)); New Jersey requires 20 days.
Example: With your new CLP you drive the school's tractor-trailer on public roads, with your instructor in the passenger seat.
Also called: CLP, learner's permit, learner permit
A commercial motor vehicle (CMV) is a heavy truck, big bus, or placarded vehicle.
A vehicle is a CMV for CDL purposes in four cases. It is rated at 26,001 pounds or more, alone or as a combination that tows more than 10,000 pounds. It seats 16 or more including the driver, or it hauls hazardous materials that need placards.
On the test
Questions ask which vehicles count as a CMV, which rules apply only in a CMV, and how CMV convictions affect your CDL.
Appears in 222 test questions
See 9 questions on the Texas testDiffers by state: The federal thresholds are printed the same everywhere. New York counts '15 or more passengers excluding the driver', which is the same 16. California also makes any 3-axle vehicle over 6,000 pounds, and any vehicle carrying more than 10 passengers, a CMV. New York, California, North Dakota, Rhode Island and Wisconsin classify by the greater of the rating, registered weight or actual weight, not the rating alone.
Does not mean: Not every work truck: the CDL definition starts at the thresholds above; FMCSA safety rules reach lighter trucks (from 10,001 pounds).
Example: The landscaping truck is light, but with the heavy equipment trailer hooked on, the combination becomes a CMV.
Also called: CMV
Class A is the CDL for heavy tractor-trailer combinations.
Federally, Class A covers any combination rated 26,001 pounds or more where the towed unit is rated over 10,000 pounds. A Class A holder may also drive Class B and C vehicles with the right endorsements.
Differs by state: The 26,001/10,000 rule is printed in every manual. California defines Class A by what you tow (any trailer over 10,000 pounds GVWR or GVW) with no 26,001 test. California, North Dakota, Rhode Island and Wisconsin use actual or registered weight when it is higher than the rating. California and Texas also issue non-commercial Class A licenses.
Does not mean: Class A is about the weight ratings of the combination, not the number of axles or the trailer length.
Example: You will pull a full-size dry van behind a tractor, so you train and test for a Class A CDL.
Also called: class a cdl, class a license
Class B is the CDL for heavy single vehicles.
Federally, Class B covers a single vehicle rated 26,001 pounds or more, which may tow a trailer rated 10,000 pounds or less. Dump trucks, cement mixers, and city buses are typical.
Differs by state: Texas puts any vehicle designed for 24 or more passengers in Class B regardless of weight. California adds any 3-or-more-axle vehicle over 6,000 pounds and any farm labor vehicle, and rates by GVWR or actual GVW. North Dakota, Rhode Island and Wisconsin also count actual or registered weight when higher than the rating. California and Texas issue non-commercial Class B licenses too.
Does not mean: Class B is about the weight rating of one vehicle, not the number of axles or passengers, except in Texas.
Example: You drive a dump truck with no trailer, so a Class B CDL is enough for the job.
Also called: class b cdl
Class C is the CDL for lighter passenger or hazmat vehicles.
The vehicle is below the Class A and B weight lines but seats 16 or more including the driver, or carries placarded hazardous materials. Small shuttle buses and some hazmat vans are typical.
Differs by state: Texas caps Class C at 16 to 23 passengers; 24 or more is Class B there. New Jersey extends Class C downward to small school buses and for-hire vans seating 8 to 15. In California, Maine, Maryland, Oregon, Texas and Wyoming the ordinary driver's license is also a 'Class C', so look for the word commercial.
Does not mean: Class C is not the ordinary car license, even though six states call their regular license Class C; a commercial Class C is a CDL.
Example: A hotel shuttle seats 20 people but weighs far less than a big truck, so its driver needs a Class C with a P endorsement.
Also called: class c cdl
A CDL code that permits a special vehicle or cargo.
The federal endorsements are T (doubles/triples), P (passenger), N (tank vehicle), H (hazardous materials), X (tank and hazmat), and S (school bus). Each needs its own knowledge test; P and S also need a skills test in that vehicle.
Differs by state: The six federal letters (T, P, N, H, X, S) are the same everywhere, but states may add their own. New York also prints F and G (farm vehicles), M (metal coil), R (recreational vehicles) and W (tow truck). Texas reuses H as a restriction code (vehicle not over 26,000 lb GVWR), so an H on a Texas license may not mean hazmat.
Does not mean: An endorsement is not a restriction: an endorsement adds a privilege, a restriction takes one away.
Example: Your company wants you to pull a fuel tanker, so you pass the tank and hazmat tests and add the X endorsement first.
Also called: endorsements
doubles/triples endorsement
이중/삼중 트레일러 추가 자격The doubles/triples endorsement (T) permits pulling two or three trailers.
You earn it with a knowledge test only; there is no extra skills test. It covers the special handling problems of multiple trailers, such as the crack-the-whip effect.
On the test
Questions ask which license and endorsement you need to pull double or triple trailers and what test the endorsement requires.
Example: A Class A driver takes a job pulling two short trailers for an LTL carrier, so he adds the T endorsement first.
Also called: T endorsement
tank and hazmat endorsement
X 추가 자격The X endorsement combines the tank and hazmat endorsements.
You need it to haul placarded hazardous materials in a tank. It requires passing both the tank and the hazmat knowledge tests, plus the hazmat background check.
On the test
Questions ask which endorsement a tanker of placarded hazardous materials requires and which tests the X endorsement covers.
Appears in 1 test question
See 1 question on the Tanker testExample: You will deliver gasoline in a cargo tank, so you take both knowledge tests and the background check to get X.
Also called: X endorsement
A CDL code that limits what vehicles you may drive.
Restrictions come from how you tested. Test in an automatic and you get E (no manual transmission); skip the air brakes test and you get L (no air brakes). Certify intrastate only and you get K.
On the test
Questions ask what a restriction does to your license and which restriction you receive after testing in a limited vehicle.
Appears in 17 test questions
See 4 questions on the HazMat testDiffers by state: The ten standardized federal codes (E, K, L, M, N, O, P, V, X, Z) are the same everywhere, but letters get reused. Texas prints H as a restriction (vehicle not over 26,000 lb GVWR), while H is the hazmat endorsement elsewhere. Minnesota adds W (buses under 24 passengers), and New York adds many state-only codes. The N restriction reads 'No Class B passenger vehicle' in Texas and Minnesota but 'No Class A and B passenger vehicle' elsewhere.
Does not mean: A restriction is not an endorsement: it takes a privilege away rather than adding one.
Example: You pass the skills test in an automatic truck, so your CDL carries an E restriction until you retest in a manual.
Also called: restrictions, restriction code
air brake restriction
공기 브레이크 제한A restriction barring you from any commercial motor vehicle (CMV) with air brakes.
You get it if you skip or fail the air brakes knowledge test, or take the skills test in a vehicle without air brakes. L means no air brakes at all; Z means no full air brakes, so air-over-hydraulic is still allowed.
On the test
Questions ask what you must pass to drive a vehicle with air brakes and what happens if you test without them.
Example: The rental truck you tested in had hydraulic brakes, so your new CDL says L and you cannot drive the air-brake tractor.
Also called: L restriction, Z restriction
The multiple-choice written exam you pass before the skills test.
Everyone takes the general knowledge test; add tests for air brakes, combination vehicles, and each endorsement you want. You must score at least 80 percent on each test. Passing them earns your commercial learner's permit (CLP).
On the test
Questions ask which knowledge tests a license class or endorsement requires and what topics those tests cover.
Appears in 5 test questions
See 2 questions on the HazMat testDiffers by state: Which tests exist and the 80 percent passing score are federal. The number of questions, waits between retakes and attempt caps are set by each state and printed inconsistently. California caps attempts per application; Rhode Island and West Virginia impose multi-day waits. Check your own state's manual.
Example: You want a Class A with air brakes, so you take the general knowledge, combination vehicles, and air brakes tests the same morning.
Also called: written test, general knowledge test
The hands-on CDL exam: inspection, basic control, and road driving.
You take it in a vehicle of the class you want. You must hold your commercial learner's permit (CLP) for a minimum period first. Each part must be passed before the next begins.
Differs by state: You must hold the CLP at least 14 days before the skills test (49 CFR 383.25(e)); New Jersey requires 20. The exercises differ by state: about half use the FMCSA Modernized test with four backing exercises. About a third still run the older six-exercise test. Texas runs both (the older test at Del Rio and Wichita Falls). Who gives the test also varies: state DMV, state police, or only third-party examiners.
Example: After the required permit wait you book the test, bring the tractor-trailer you trained in, and start with the inspection.
Also called: road test, driving test
basic vehicle control skills test
기본 차량 조작 기능 시험The skills-test part where you back and turn inside a marked area.
Cones and lines mark the area. Exercises include straight-line backing and offset backing; older tests add parallel parking and alley dock. Crossing a line or hitting a cone loses points.
Differs by state: The exercise list depends on which test your state uses. The FMCSA Modernized test has Forward Stop, Straight-Line Backing, Forward Offset Tracking and Reverse Offset Backing. The older 2005/2017 test has Straight Line Backing, Offset Back right and left, Parallel Park driver side and conventional, and Alley Dock. Roughly half the states are Modernized, a third legacy, and six, including Texas and Georgia, run both; study your own state's list.
Example: The examiner points to the cones and asks for a straight-line back; you check both mirrors and back slowly between them.
Diagram coming
Also called: basic control skills, backing test
pre-trip inspection
출발 전 점검A check of the whole vehicle before driving.
The driver, not the mechanic, is responsible for it. It is also the first part of the skills test, where you point to each part and explain what you check and why.
Example: Before leaving the yard you walk around the truck, check tires, lights, and air lines, and find a cut brake hose.
Also called: pre-trip, vehicle inspection, pre-trip inspection test
An eye exam checking sharpness, side vision, and color recognition.
It is part of the DOT physical and is also done at the licensing office. The federal standard is at least 20/40 in each eye, with or without correction, plus a 70-degree field of view in each eye. Glasses or contacts are allowed; if you need them, your license says so.
Example: At the DMV window you read the chart with your glasses on, so your license carries a corrective-lenses restriction.
medical examiner's certificate
신체검사 증명서 (DOT 메디컬 카드)The card proving you passed the DOT physical.
It is often called the medical card or DOT card. Most drivers need a current one on file with the state to keep a CLP or CDL. It is valid for up to 24 months, shorter if the examiner wants to monitor a condition.
Differs by state: Since mid-2025 most states no longer accept the paper card from the driver. The examiner sends the result electronically through FMCSA's National Registry to the licensing agency. Cutover dates differ (June 2025 in most states, Georgia and Michigan slightly earlier). Arizona still takes paper from intrastate drivers, and California wants the long-form report as well as the card; check your state's current process.
Example: Your card expires next month, so you book a DOT physical now, because the state will downgrade your CDL without a current one.
Also called: medical card, DOT medical card, medical certificate
The federal medical exam that certifies a driver fit to drive.
Only an examiner listed on FMCSA's National Registry may do it. It checks vision, hearing, blood pressure, and other conditions that affect safe driving. Passing it earns the medical examiner's certificate.
On the test
Questions ask who must take the exam, who may perform it, and how it connects to your medical certificate.
Example: Before your first trucking job you visit a registry doctor, pass the DOT physical, and leave with your medical card.
Also called: DOT medical exam, medical exam
Loss of the right to drive a commercial motor vehicle (CMV) after certain convictions.
A first major offense (DUI, leaving a crash scene, a felony with a vehicle) costs at least one year; a second costs life. Two serious traffic violations within three years cost at least 60 days; three cost at least 120 days. Driving in violation of an out-of-service order or breaking railroad-crossing rules also disqualifies you.
On the test
Questions ask which convictions disqualify you, for how long on a first and second offense, and how out-of-service or railroad-crossing violations count.
Appears in 57 test questions
See 3 questions on the New York testDiffers by state: The major-offense and serious-violation periods read the same in every manual and match 49 CFR 383.51. Maryland lists four railroad-crossing offenses instead of six because Maryland law makes every CMV stop at every crossing. Deadlines to notify your employer differ too: within two business days in most manuals, by the next business day in Michigan and California.
Does not mean: Disqualification is not a suspension of your regular license: it is the CMV privilege that is taken, sometimes while you keep driving your car.
Example: A driver convicted twice in three years of ignoring a railroad crossing rule is disqualified even though no crash happened.
Also called: disqualified
A temporary loss of your license; revocation cancels it outright.
Either one on your regular license also stops your CDL. Two serious traffic violations in a CMV within three years cost at least 60 days. Alcohol, drug, or felony actions on any license cost at least one year, or life on repeat.
Differs by state: The federal minimum periods are printed the same everywhere. The deadline to tell your employer differs. Most manuals print 'within two business days'. Federal rule 49 CFR 383.33, and the Michigan and California manuals, say by the end of the next business day. Kentucky, Montana and Maryland state the duty with no time limit.
Does not mean: Not the vehicle's suspension system (springs, shocks, air bags) that you check in the pre-trip inspection.
Example: Your car license is suspended after a speeding conviction in your own car, so you cannot drive the truck either until it is restored.
Also called: revocation, revoked
out of service
운행 정지 명령 (OOS)An inspector's order that stops a driver or vehicle from operating.
A vehicle goes out of service for unsafe defects. A driver goes out of service for alcohol in the system, missing papers, hours violations, or failing the roadside English check (since June 2025). Alcohol below the 0.04 BAC limit still means 24 hours out of service; driving in violation of the order is itself a disqualifying offense.
Differs by state: The alcohol trigger diverges: most manuals say any detectable amount under 0.04 puts you out of service for 24 hours. Michigan prints a 0.015 floor instead (needs source verification), and Kentucky prints a 0.01 to 0.039 band.
Example: The inspector finds a brake out of adjustment and a cracked air hose, so the truck sits until a mechanic fixes both.
Also called: out-of-service order, OOS
roadside inspection
도로변 검사 (DOT 검사)An officer's check of the driver, papers, and vehicle on the road.
Federal and state inspectors may inspect any CMV. Levels range from a full driver-and-vehicle inspection to a papers-only check. Out-of-adjustment brakes are the most common defect found.
Example: At the scale you are waved into the inspection bay; the officer checks your license, logs, and medical card, then crawls under the trailer.
Also called: DOT inspection
A roadside checkpoint where trucks are weighed and may be inspected.
Trucks must usually pull in when the station is open unless a sign or bypass device clears them. Officers check weight, papers, and sometimes do a full inspection there.
Differs by state: Who must stop (trucks only, or buses too) and the weight that triggers it are set by each state. So is whether a bypass transponder is honored; the manuals barely cover it.
Example: The sign says the scales are open, so you take the exit, roll across the scale slowly, and wait for the green light.
Also called: scale house, scales
The U.S. Department of Transportation (DOT), the federal department that oversees trucking.
FMCSA, which writes the CDL and safety rules, is part of DOT. Drivers meet the name on the DOT physical, DOT numbers on trucks, DOT hazard classes, and DOT inspections.
On the test
Questions use DOT in names: the DOT hazard classes, DOT tank specifications, and the DOT medical exam.
Appears in 106 test questions
See 8 questions on the HazMat testDoes not mean: DOT is the federal department; a state DOT (TxDOT, NYSDOT) builds roads and is a different agency.
Example: The officer asks for your DOT medical card and checks the DOT number painted on the cab door.
Also called: Department of Transportation
FMCSA
FMCSA (연방 자동차 운송 안전청)The Federal Motor Carrier Safety Administration (FMCSA) writes the federal trucking rules.
It runs the National Registry of medical examiners, the Training Provider Registry for ELDT, and the Drug and Alcohol Clearinghouse. States issue the CDL, but they follow FMCSA's rules in 49 CFR.
Example: Your school must be listed on FMCSA's Training Provider Registry, or the state will not let you take the skills test.
Also called: Federal Motor Carrier Safety Administration
Hours of service (HOS) are the federal limits on driving and work time.
Under the federal rules you may drive 11 hours inside a 14-hour window, after 10 hours off duty. Take a 30-minute break after 8 hours of driving; the week caps at 60 hours in 7 days or 70 in 8. A 34-hour restart resets the week; your logbook or ELD tracks all of it.
Differs by state: The federal numbers are identical in every manual that prints them, and those are the numbers above. Intrastate-only drivers may fall under a state scheme instead. California prints its own 12-hour driving, 16-hour on-duty and 80-hours-in-8-days rules beside the federal set. North Dakota prints no numbers and refers intrastate drivers to the Highway Patrol.
Example: Your ELD shows little driving time left, so you stop at a truck stop for the night instead of pushing on.
Diagram coming
Also called: HOS
All working time from the start of your day until released.
Inspecting the truck, fueling, loading, waiting at a dock, and paperwork all count as on duty, not driving. On-duty time runs the daily window and the weekly cap; only off-duty and sleeper time are outside it.
Example: You wait most of the morning at the receiver to unload; that is on duty, and your daily window keeps running.
Also called: on duty
The bed compartment in a truck cab used for logged rest.
Sleeper berth is one of the four duty statuses on your log. Your required daily off-duty rest may be split into two periods if enough of it is spent in the sleeper.
On the test
Questions ask how sleeper-berth time fits the hours-of-service rules and where it appears among the duty statuses.
Appears in 4 test questions
See 2 questions on the HazMat testDiffers by state: Federal law (49 CFR 395.1(g)) allows a split of at least 7 consecutive sleeper hours plus at least 2 more hours, totaling 10. Older manual editions, including California's, still print the pre-2020 rule of one period not less than 8 hours.
Example: You need rest but have hours left for tomorrow, so you log a long block in the sleeper berth and finish the split later.
The 11-hour limit caps driving time after a full rest.
After 10 consecutive hours off duty you may drive up to 11 hours. The 11 hours must also fit inside the 14-hour window, and a 30-minute break interrupts them.
On the test
Questions ask how many hours you may drive after a rest period and how that limit relates to the duty window.
Differs by state: Federal interstate rule. California intrastate drivers get 12 hours; other states may set their own intrastate limits.
Example: Your ELD shows nearly 11 hours of driving today, so you park before the limit even though the delivery is close.
The 14-hour limit is the daily window for all driving.
The clock starts when you begin work and does not stop for breaks, waiting, or off-duty time. Once 14 hours pass you may work, but not drive, until you take 10 hours off.
On the test
Questions ask how long after coming on duty you may still drive and whether breaks extend that window.
Differs by state: Federal interstate rule. California's intrastate rule is 16 hours on duty; other states may differ for intrastate drivers.
Does not mean: The 14 hours are not driving hours: only 11 of them may be spent driving.
Example: A long wait at the shipper ate into your day; the 14-hour window ends before you can reach the receiver, so you stop.
Diagram coming
The 30-minute break is the required pause after long driving.
After 8 cumulative hours of driving without a half-hour interruption, you must take at least 30 minutes not driving. Off duty, sleeper berth, or on duty not driving all count.
On the test
Questions ask when a break is required and what kinds of time satisfy it.
Example: Eight hours of driving are coming up, so you plan fuel and lunch together and log the 30 minutes before continuing.
60/70-hour limit
60/70시간 제한The 60/70-hour limit caps on-duty hours over 7 or 8 consecutive days.
Carriers that do not run every day use 60 hours in 7 days; those that run daily may use 70 in 8 days. The count is rolling. A 34-hour restart resets it.
On the test
Questions ask the weekly on-duty caps and which schedule a carrier may use.
Differs by state: Federal interstate rule. California intrastate drivers have 80 hours in 8 days (112 when hauling farm products).
Does not mean: Not the fatigue statistic that working over 60 hours a week raises crash risk; that is a different fact sharing the number.
Example: By Friday your weekly total is near 70, so dispatch gives you a long weekend off to reset the clock.
34-hour restart
34시간 재시작 (리스타트)A 34-hour off-duty period that resets the weekly count.
Take at least 34 consecutive hours off duty and your 60/70-hour total starts again from zero. It is optional; without it the count rolls forward day by day.
On the test
Questions ask how a driver resets the weekly limit and how long the restart must be.
Example: You finish Thursday night and do not touch the truck until Saturday morning, so Saturday starts with a fresh weekly clock.
The daily record of your hours by duty status.
Its formal name is record of duty status (RODS); today most drivers keep it on an electronic logging device (ELD). Inspectors can ask for the current day and the previous seven. Falsifying it is a serious offense.
Example: The officer asks for your logs; you show the ELD display for today and the past week and hand over the instruction card.
Also called: record of duty status, RODS
electronic logging device
ELD (전자 기록 장치)An electronic logging device (ELD) records driving time automatically from the engine.
It logs when the truck moves and where it is; you enter the other duty statuses yourself. Most interstate carriers must use one instead of paper logs. Edits are flagged, and you must carry its instruction card.
Does not mean: An ELD is not a live feed to FMCSA: your carrier sees the data; officers see it at an inspection.
Example: You start the truck and the ELD switches you to driving by itself; at the dock you tap on duty, not driving.
Also called: ELD
driver vehicle inspection report
DVIR (운전자 차량 점검 보고서)Full entryA driver vehicle inspection report (DVIR) is the written end-of-day defect report.
You fill it out after your post-trip inspection and list anything that affects safety or could cause a breakdown. The carrier must fix or clear each item. The next driver reviews it and signs only if defects were listed and certified.
Example: You note a weak trailer brake light on the DVIR; the next morning the shop has signed it off as repaired before you leave.
Also called: DVIR, vehicle inspection report, post-trip inspection
entry-level driver training
ELDT (초급 운전자 교육)Entry-level driver training (ELDT) is the required course before a first CDL.
It applies to a first Class A or B CDL, an upgrade from B to A, and a first school bus, passenger, or hazmat endorsement. You may get your CLP first, but the training must be finished before the skills test or the hazmat knowledge test. The provider must be listed on FMCSA's Training Provider Registry, which tells the state you finished; the rule took effect February 7, 2022.
On the test
Questions ask who must complete ELDT and when the requirement took effect.
Differs by state: The federal effective date is February 7, 2022 and most manuals print it; Montana's manual prints November 13, 2023 instead. Drivers who held a CLP before the federal date were grandfathered until that permit expired.
Example: Your cousin got his CDL years ago without a school, but today you must finish ELDT before the skills test.
Also called: ELDT
training provider registry
교육 기관 등록부 (TPR)FMCSA's list of training providers whose entry-level driver training (ELDT) counts.
Before your first CDL skills test, you must complete ELDT. The school must be on this list, or the training does not count. The school reports your completion to the registry, and your state checks it electronically.
On the test
Not on the knowledge test; you meet the registry when you choose a school and when the state checks your training record.
Does not mean: A listing is not a quality rating; FMCSA lists providers on their own attestation and audits them afterwards.
Example: Before paying a school, you search the registry website and confirm the school's name and location are listed.
Also called: TPR
Drug and Alcohol Clearinghouse
FMCSA's database of CDL drivers' drug and alcohol test violations.
A failed or refused DOT drug or alcohol test is recorded here under your name. While a violation is unresolved, you may not drive a commercial motor vehicle (CMV). Employers check the database before hiring you and every year after, and the state checks it when it issues your CDL.
On the test
Not on the knowledge test; the test covers alcohol rules and BAC, while the Clearinghouse matters when you apply for a job or a license.
Does not mean: It is not the medical certificate and not a card you carry; it is a record employers and the state query online.
Example: A carrier offers you a job, then asks you to log in and give consent so it can run a Clearinghouse query.
Also called: Clearinghouse
English language proficiency
영어 구사 능력 (ELP)The federal rule that a CMV driver must read and speak enough English.
At a roadside inspection, the officer talks to you in English and may ask you to explain road signs. Since June 2025, a driver who fails this check is placed out of service on the spot. No interpreter or phone app is allowed during the check.
On the test
Not on the knowledge test; the skills test is given in English only, and this roadside check comes after you are licensed.
Does not mean: It is not a grammar or accent test; it checks whether you can answer questions, follow directions, and understand signs.
Example: An officer at a weigh station asks where you are coming from and what you are hauling; you answer in English.
Also called: ELP
gross vehicle weight rating
GVWR (차량 총중량 등급)Full entryThe maximum loaded weight of a single vehicle, set by its manufacturer.
It is a rating printed on a label, not what the truck weighs today. A single vehicle rated 26,001 pounds or more needs a CDL. The CDL class you need depends on this rating, and on the trailer's rating when you tow.
Differs by state: Most states set the CDL class by the manufacturer's rating alone; North Carolina says so outright and bars actual weight. North Dakota, Rhode Island and Wisconsin use the greater of the rating and the actual or registered weight. California writes 'GVWR or GVW' throughout, and New York law uses the greatest of GVWR/GCWR, registration weight and actual weight.
Does not mean: GVWR is not the actual weight on the scale; that is gross vehicle weight (GVW).
Example: You read the door-jamb label of a straight truck to see its GVWR before deciding which license class covers it.
Also called: GVWR
gross combination weight rating
GCWR (결합 차량 총중량 등급)The manufacturer's maximum loaded weight for a tractor plus its trailers.
If the power unit's label does not show a GCWR, add the ratings of the truck and each towed unit. Class A is decided by GCWR together with the trailer's GVWR.
Differs by state: Most states set the CDL class by the manufacturer's rating alone; North Carolina says so outright and bars actual weight. North Dakota, Rhode Island and Wisconsin use the greater of the rating and the actual or registered weight. California writes 'GVWR or GVW' throughout, and New York law uses the greatest of GVWR/GCWR, registration weight and actual weight.
Does not mean: Not the weight on the scale; that is gross combination weight (GCW).
Example: A tractor's label shows its GCWR; you compare it with the loaded weight of your rig on the scale ticket.
Also called: GCWR
gross vehicle weight
GVW (차량 총중량)The actual weight of a single vehicle with its load.
This is what the truck really weighs right now, load included. It changes every time you load or unload; the rating (GVWR) does not change.
Differs by state: In most states only the rating decides your CDL class. In North Dakota, Rhode Island, Wisconsin, California and New York the actual or registered weight can raise the class when higher than the rating.
Does not mean: Not the rating on the label; GVW is the actual weight, GVWR is the maximum allowed.
Example: The weigh station scale shows the GVW of your straight truck with today's cargo on board.
Also called: GVW
gross combination weight
GCW (결합 차량 총중량)The actual weight of a power unit, its trailers, and cargo.
It is the number the scale shows for the whole rig. Compare it with the GCWR and with legal weight limits before you drive.
Does not mean: Not the manufacturer's rating; that is GCWR.
Example: After loading, you pull onto a truck-stop scale and the ticket shows the GCW of tractor, trailer and freight.
Also called: GCW
The weight one axle, or one set of axles, puts on the road.
States limit how much weight each axle may carry, not just the total. Sliding the trailer tandems or the fifth wheel moves weight between axles.
Differs by state: Legal axle limits are set by each state. Maryland's manual describes axle weight as a capacity rather than an actual load. Washington, Minnesota and North Dakota print tire-load limits in pounds per inch of tire width that other manuals do not state.
Example: The scale shows your drive axles are over the limit, so you slide the trailer tandems forward to shift weight.
Diagram coming
A rule allowing less axle weight when axles are closer together.
Weight spread over a long distance is easier on a bridge than the same weight bunched up. So axles that sit close together may carry less.
Example: Spreading the trailer tandems farther apart lets your rig carry more weight legally on those axles.
Diagram coming
Also called: bridge law
Breaking a traffic law while driving; serious ones can cost you your CDL.
Serious traffic violations include speeding 15 mph or more over the limit, reckless driving, improper lane changes, and following too closely. Two of them in a CMV within three years cost your CDL for at least 60 days; three cost at least 120 days. You must also tell your employer within 30 days of any conviction except parking, in any vehicle.
On the test
Questions ask which offenses count as serious traffic violations, how many trigger a disqualification, and how soon you must notify your employer.
Appears in 15 test questions
See 3 questions on the General Knowledge testDiffers by state: Newer manuals such as New York's also list handheld phone use or texting while driving a CMV as serious traffic violations. That matches federal rules; older printings such as Texas's omit them.
Does not mean: A parking ticket is not a traffic violation for the reporting rule.
Example: You get a speeding ticket in your personal car on a day off; you still must tell your employer after the conviction.
Also called: moving violation
A serious crime; committing one with a vehicle costs you the CDL.
Using a vehicle to commit a felony disqualifies you for at least one year, or three years if the CMV carried placarded hazmat. A second offense, or a felony involving controlled substances, means losing the CDL for life.
Does not mean: Not every crime is a felony; it is the serious category, above a misdemeanor.
Example: A driver uses a personal car to transport illegal drugs and is convicted; the CDL is revoked even though no truck was involved.
