License, rules and roadside

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.

Not the same as: A CDL is not a heavier car license: it is federally standardized, and a CDL holder may not keep a second driver's license.

A 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.

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.

Not the same as: Not every work truck: the CDL definition starts at the thresholds above; FMCSA safety rules reach lighter trucks (from 10,001 pounds).

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.

Not the same as: Class A is about the weight ratings of the combination, not the number of axles or the trailer length.

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.

Not the same as: Class B is about the weight rating of one vehicle, not the number of axles or passengers. Texas also counts passengers, and California also counts axles.

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.

Not the same as: 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.

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.

Not the same as: An endorsement is not a restriction: an endorsement adds a privilege, a restriction takes one away.

The 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.

The 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.

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.

Not the same as: A restriction is not an endorsement: it takes a privilege away rather than adding one.

A 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.

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).

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.

The 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.

A 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.

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.

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.

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.

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.

Not the same as: Disqualification is not a suspension of your regular license: it is the CMV privilege that is taken, sometimes while you keep driving your car.

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.

Not the same as: Not the vehicle's suspension system (springs, shocks, air bags) that you check in the pre-trip inspection.

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.

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.

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.

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.

Not the same as: DOT is the federal department; a state DOT (TxDOT, NYSDOT) builds roads and is a different agency.

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.

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.

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.

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.

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.

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.

Not the same as: The 14 hours are not driving hours: only 11 of them may be spent driving.

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.

The 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.

Not the same as: Not the fatigue statistic that working over 60 hours a week raises crash risk; that is a different fact sharing the number.

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.

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.

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.

Not the same as: An ELD is not a live feed to FMCSA: your carrier sees the data; officers see it at an inspection.

A 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.

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.

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.

Not on the knowledge test; you meet the registry when you choose a school and when the state checks your training record.

Not the same as: A listing is not a quality rating; FMCSA lists providers on their own attestation and audits them afterwards.

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.

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.

Not the same as: It is not the medical certificate and not a card you carry; it is a record employers and the state query online.

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.

Not on the knowledge test; the skills test is given in English only, and this roadside check comes after you are licensed.

Not the same as: It is not a grammar or accent test; it checks whether you can answer questions, follow directions, and understand signs.

The 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.

Not the same as: GVWR is not the actual weight on the scale; that is gross vehicle weight (GVW).

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.

Rarely asked directly; questions use it inside Class A definitions and ask how a rating differs from actual weight.

Not the same as: Not the weight on the scale; that is gross combination weight (GCW).

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.

Not the same as: Not the rating on the label; GVW is the actual weight, GVWR is the maximum allowed.

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.

Not the same as: Not the manufacturer's rating; that is GCWR.

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.

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.

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.

Not the same as: A parking ticket is not a traffic violation for the reporting rule.

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.

Not the same as: Not every crime is a felony; it is the serious category, above a misdemeanor.