General Knowledge Practice Test
Every CDL applicant in the United States must pass the General Knowledge exam, regardless of the class of license or endorsements being sought. The test is built directly from the AAMVA Commercial Driver License Manual and covers driver qualifications, vehicle inspection, basic vehicle control, shifting, communicating with other drivers, controlling speed and space, seeing hazards, distracted and aggressive driving, fatigue, hazardous-materials awareness, and accident procedures. Most states ask 50 multiple-choice questions and require a score of at least 80% to pass.
How to use this practice bank
Read each question carefully before checking the answer. Most CDL questions are not designed to trick you, but they do test whether you know the specific rule — not just what feels safe. After reading the explanation, try to restate the rule in your own words; if you can, you've internalized it. If you can't, look up the corresponding chapter of your state's CDL handbook before moving on.
Pass scores vary slightly by state, but most jurisdictions require at least 80% correct on each knowledge exam. With 228 questions in this bank you have substantially more practice material than any single sitting of the real exam, which typically contains 20 to 50 questions per endorsement.
All 228 questions in this bank
- #1You are driving on a straight, level highway at 50 mph. There are no vehicles in front of you. Suddenly, a tire blows out on your vehicle. What should you do first?
- #2You are driving a new truck with a manual transmission. What gear will you probably have to use to take a long, steep downhill grade?
- #3You are checking your wheels and rims for a pre-trip inspection. Which of these statements is true?
- #4You are checking your tires for a pre-trip inspection. Which of these statements is true?
- #5If a straight vehicle (not trailer or articulation) goes into front-wheel skid, it will:
- #6If you need to leave the road in a traffic emergency, you should:
- #7Which of these statements about certain types of cargo is true?
- #8According to the driver’s manual, why should you limit the use of your horn?
- #9You do not have a hazardous materials endorsement on your commercial driver’s license. You are asked to deliver hazardous materials in a placarded vehicle. You should:
- #10Which of these statements about staying alert to drive is true?
- #11Your vehicle has hydraulic brakes. While travelling on a level road, you press the brake pedal and find that it goes to the floor. Which of the statements is true?
- #12You are driving a vehicle at 55 mph on dry pavement. About how much total stopping distance will you need to bring it to a stop?
- #13Which of these statements about cold weather driving is true?
- #14When driving at night, you should:
- #15Which of these statements about downshifting is true?
- #16For your safety, when setting out reflective triangles, you should:
- #17Which of these statements about backing a heavy vehicle is true?
- #18As the blood alcohol concentration (BAC)goes up, what happens?
- #19What will help keep an engine cool in hot weather?
- #20Which of these is a good thing to remember about using mirrors?
- #21Cargo that is not loaded or secured properly can cause:
- #22Hydroplaning:
- #23When driving through a work zone, you should:
- #24If you are being tailgated, you should:
- #25A key principle to remember about loading cargo is to keep the load:
- #26How far should a driver look ahead of the vehicle while driving?
- #27How do you correct a rear-wheel acceleration skid?
- #28The purpose of the retarders is to:
- #29Controlled braking:
- #30Which of these is a good thing to do when steering to avoid the crash?
- #31You should stop driving.
- #32Escape ramps are:
- #33Which of these items is checked in a pre-trip inspection?
- #34Which of these is not a good rule to follow when caring for injured persons at an accident scene?
- #35You are checking your steering and exhaust system in a pre-trip inspection. Which of these problems, if found, a hould be fixed before the vehicle is driven:
- #36You should avoid driving through deep puddles or flowing water. But if you must, which of these steps can help keep your brakes working?
- #37Which of these statements about drugs is true?
- #38Which of these is a good thing to remember when crossing or entering traffic with a heavy vehicle?
- #39You are driving a heavy vehicle with a manual transmission. You have to stop the vehicle on the shoulder while driving on an uphill grade. Which of these is a good rule to follow when putting it back in motion up the grade?
- #40You are driving a heavy vehicle. You must exit a highway using an off-ramp that curves downhill. You should:
- #41You must park on the side of a level, straight, four-lane divided highway. Where should you place the reflective triangles?
- #42You are driving on a two-lane road. An oncoming driver drifts into your lane and is headed straight for you. Which of these is most often the best action to take?
- #43Which of these is proper use of vehicle lights?
- #44Brake “fade”:
- #45Which of these statements about engine overheating is true?
- #46Which of these statements about overhead clearance is true?
- #47Which of these statements about vehicle fire is true?
- #48You are driving a long vehicle that makes wide turns. You want to turn left from Pine Street on to Cedar Street. Both are two-lane two-way streets. You should:
- #49You must drive on a slippery road. Which of these is a good thing to do in such a situation?
- #50Which of these statements about acceleration is true?
- #51Which of these statements about braking is true?
- #52When the roads are slippery, you should:
- #53You are checking your brakes and suspension system for a pre-trip inspection. Which of these statements is true?
- #54Which of these pieces of emergency equipment should always be carried in your vehicle?
- #55Which of these can cause a vehicle to skid?
- #56The driver’s manual suggests several things to do when you pass a vehicle. Which of these is not one of them?
- #57The distance that you should look ahead of your vehicle while driving amounts to about___ miles at normal highway speed.
- #58You are starting your vehicle in motion for a stop, as you apply power to the drive wheels, they start to spin. You should:
- #59Which of these is the most important thing to remember about emergency braking?
- #60Which of these statements about tire and hot weather driving is true?
- #61You should use mirrors to check:
- #62Your vehicle is in a traffic emergency and may collide with another vehicle if you do not take action. Which of these is a good rule to remember at such a time?
- #63Which of these statements about speed management is true?
- #64Which fires can you use water to put out?
- #65To help you stay alert while driving, you should:
- #66To avoid a crash, you have to drive into the right shoulder. You are now driving 40 mph on the shoulder. How should you move back onto the pavement?
- #67Which of these statements about driving in areas with strong wind is true?
- #68Which of these is a good thing to do when driving at night?
- #69You are driving a 40-foot vehicle at 35 mph. The road is dry and visibility is good. What is the least amount of space you should keep in front of your vehicle to be safe?
- #70What is the proper way to hold a steering wheel?
- #71High beams should be:
- #72You can see a marking on a vehicle ahead of you. The marking is a red triangle with an orange center. What does the marking mean?
- #73Which of these is not part of the pre-trip inspection of the engine compartment?
- #74The road you are driving on becomes very slippery due to glare ice. Which of these is a good thing to do in such a situation?
- #75Which of these is a sign of tire failure?
- #76You wish to turn right from one two-lane, two-way street to another. Your vehicle is so long that you must swing wide to make the turn. Which of these figures shows how the turn should be made?
- #77You are driving a vehicle that could safely be driven at 55mph on an open road. But traffic is heavy, and other vehicles drive at 35 mph, through the speed limit is 55 mph. The safest speed for your vehicle is more likely to be:
- #78What is counter steering?
- #79Which of these can cause a fire?
- #80Which of these is a good thing to remember about drinking alcohol?
- #81Which of these statements about backing a heavy vehicle is true?
- #82Which of these statements about marking a stopped vehicle is true?
- #83Which of these best describes how you should use the brake pedal on a steep downhill grade?
- #84Which of these statements about using turn signals is true?
- #85Which of these statements about double clutching and shifting is true?
- #86Which of these would tell you that a shipment contains hazardous materials?
- #87Which of these statements about speed management is true?
- #88Retarders:
- #89A route inspection should include checking for:
- #90To connect a drive wheel braking skid, you should:
- #91When exiting or entering on a curved freeway ramp, you should:
- #92On which fires can you use the “ ABC” fire extinguisher?
- #93Which of the following vehicles will have the longest stopping distance?
- #94How many red reflective triangles are you required to carry?
- #95You are required to inspect your truck within how many miles after beginning the trip?
- #96There are two types of jack knife, they are:
- #97The new BAC (Blood Alcohol Concentration) for commercial drivers to be considered intoxicated when driving a commercial vehicle is:
- #98Where should the ignition key be during the pre-trip inspection?
- #99When loading a trailer, if the load is loaded all to the rear, it may result in:
- #100Communication means:
- #101If you are convicted for driving under the influence while driving a commercial vehicle, and this is your first offence, you most likely will get:
- #102If you are stopped at the roadside rest and found to have a BAC (Blood Alcohol Concentration), you will:
- #103Which of the following statements about speed management is true?
- #104You are driving a long vehicle that makes wide turns. You want to make a left turn from Elm Street onto Oak Street. There are two left turn lanes (marked A and B) on Elm Street. Oak Street is a four-lane street with two lanes in each direction. You should:
- #105You are traveling down a long, steep hill. Your brakes get so hot that they fail. What should you do?
- #106The center of gravity of a load:
- #107To prevent a load from shifting, there should be at least one tiedown for every ____ feet of cargo.
- #108While driving, ice builds up on your wipers and they no longer clean the windshield. You should:
- #109When the hydraulic brakes fail while you are driving, the system will not build up pressure, and the brake pedal will feel spongy or go to the floor. What should you do?
- #110Which may be a sign of the tire failure?
- #111To prevent brake fade, you should:
- #112A full stop is required at a railroad crossing when:
- #113When driving at night, you should use your low beams when an oncoming vehicle is within how many feet?
- #114When driving through a work zone, you should:
- #115Backing of a commercial vehicle is:
- #116When you are parking at the side of the road at night, you must:
- #117You must stop on a hill or curve on a two-lane two-way road. How far should you place reflective triangles?
- #118Stab braking should not be used on a vehicle with:
- #119Which of these statements about marking a stopped vehicle is true?
- #120Sometimes you need to leave a road to avoid a hazard or emergency. When you do so, you should keep in mind that:
- #121Which of the following is NOT characteristic of the front tire failure?
- #122Most skids:
- #123In bad weather, many car drivers tailgate large vehicles. What should you do?
- #124Which of the following systems should receive extra attention during winter weather inspection?
- #125What happens to tar on the road pavement during hot weather?
- #126What is the best advice for a driver when a heavy fog is on curves?
- #127In mounting driving, you will have to use a lower gear to drive safely on a grade. Which of these does NOT affect your choice of gear?
- #128What should you do before driving on mountains?
- #129Escape ramps:
- #130Which of these is true about notifying the authorities after an accident occurs?
- #131If you are not sure what to use to put out a hazardous materials fire, you should:
- #132Which of these is NOT a danger of a rough acceleration?
- #133Which of the lights cannot be checked at the same time?
- #134You are inspecting hydraulic brakes. You should pump the brake pedal three times, then apply firm pressure to the pedal for five seconds. If the brakes are working properly, the pedal should:
- #135Drivers of trucks and tractor-trailers with cargo must check that the cargo is well secured within the first ___ miles of the trip.
- #136When starting a bus on a level surface with good traction, there is often no need for:
- #137How does the weight of the vehicle affect stopping?
- #138When you are starting to move up a hill from a stop:
- #139Which is a truth about using a heater?
- #140Why is a damaged exhaust system a danger?
- #141Which of these is NOT a danger when an automatic transmission is forced into a low gear at a high speed?
- #142Perception distance is the distance your vehicle travels from the time:
- #143Extra care is needed to keep your vehicle centered in your lane because commercial vehicles:
- #144You should lightly apply your brakes to flash the brake light if:
- #145Merging onto the road is safest if you:
- #146Which of these is NOT something you should do if your headlights are not working properly?
- #147Which of the statements about backing a heavy vehicle is not true?
- #148The distance that you should look ahead of your vehicle while driving is about ___at low speed.
- #149Which of these is correct about emergency or evasive action?
- #150What does emergency braking mean?
- #151When driving in cold weather, your tire tread should:
- #152Which of these is true about hauling of hazardous material?
- #153Which vehicle will have the most difficulties staying in its lane during strong winds?
- #154Why does your vehicle speed naturally increase on a downgrade?
- #155During the vehicle inspection checking of ____ will NOT prevent a fire?
- #156When is it necessary to learn how a fire extinguisher works?
- #157What is the most important reason to inspect your truck or bus?
- #158You are checking your steering exhaust system in a pre-trip inspection. Which of these problems, if found, should be fixed before the vehicle is driven:
- #159Convex (curved) mirror:
- #160Why is it important to shift gears correctly?
- #161What three distances build up the total stopping distance of your truck or bus?
- #162Which of these actions are not recommended for a left turn?
- #163When you are passing other vehicles, pedestrians, or bicycles, you should assume that:
- #164In your mirror, you see a car approaching from the rear, the next time you check your mirror, you do not see the car, you wish to change lanes; you should:
- #165Which of these is a proper way to signal to change lane?
- #166You are driving in an area with a few street lights. If you cannot see well with your headlights, which of these actions may help:
- #167Most serious skid results from:
- #168What should be true about other drivers?
- #169What is true about bad weather and driving conditions?
- #170Which of these statements of hazard of vehicle fire is true?
- #171You should wear a seat belt in a moving vehicle.
- #172Which of these items is not checked for a pre-trip inspection?
- #173Which of the statements about pre-trip inspection is true?
- #174Can state inspectors inspect your truck or bus?
- #175Which of the statements about cargo loading is true?
- #176Which of these is not required knowledge for a driver who needs a hazardous material endorsement?
- #177To determine the alcohol concentration level for an individual, it is necessary to know.
- #178Implied consent means:
- #179The engine brake effect is greater when the engine is____ Governed RPM and the transmission is on a ____ gear.
- #180You are driving a 40-foot vehicle at 55 mph. The road is dry and visibility is good. What is the last amount of space that you need to have in front of your vehicle?
- #181What should you do if the car coming toward you at night keeps its high beams on?
- #182If you must stop into the oncoming lane as you make a turn, you should:
- #183Which of these is true about driving in a tunnel?
- #184You should use your mirror to check:
- #185You should use your horn when:
- #186If a coolant container is a part of a pressurized system, which of these is true:
- #187Which of these is a danger of crossing a railroad track on a dirt road?
- #188The tread depth on a front steering wheel's tires should be:
- #189Your vehicle will be put out of service if ____ or more leaves in any leaf spring are missing.
- #190Brake drums (or discs) must not have cracks longer than___ the width of the friction area.
- #191A hazard:
- #192You are driving a heavy vehicle. You must exit a highway using an off-ramp that curves downhill. You should:
- #193Which of these rigs has more chances to “off-track” while making a urn?
- #194How much space in front of you is needed while driving on a highway?
- #195Medicine used to treat the common cold:
- #196Which of these should you not do in an emergency situation?
- #197The primary cause of fatal crashes is:
- #198A car suddenly cuts in front of you, creating a hazard. Which of the actions should you NOT take?
- #199What should you do when you see a hazard in the roadway ahead of you?
- #200If your brakes fail on a downgrade, you must first:
- #201You should always turn on your emergency four-way flashers when you:
- #202Should brake adjustment be checked often?
- #203Which of these is true about mirror adjustments?
- #204When you're driving on a snow-packed road, you should reduce your speed by:
- #205The bridge formula:
- #206Which of these is true about hours of service?
- #207Which of these is true about the use of drugs while driving?
- #208Which of these is true about the proper use of a steering wheel?
- #209When do you need a helper to back your vehicle?
- #210To avoid an accident, you moved to the shoulder to return to the road:
- #211Which of these would not help if the windshield is covered with ice?
- #212Which og these tells you that the shipment contains hazardous materials?
- #213Heavy vehicles often move slower than others do. Which of these is NOT a good rule to follow while driving a heavy vehicle?
- #214Why might tourists be a hazard?
- #215What keeps an engine cool in hot weather driving?
- #216Cargo inspections:
- #217A vehicle is loaded with very little weight on the drive axle. What may happen?
- #218If your vehicle catches fire while you are driving, you should:
- #219Turn signals should be used:
- #220Containerized loads:
- #221When driving a commercial vehicle with a height over 13 feet, you should:
- #222When should you test your parking brake?
- #223When going down a long or steep downgrade, you should always:
- #224Controlled braking is:
- #225If you lose braking power while going down a steep hill. What is the first thing to do?
- #226If you do not have a CB radio, what is the first thing to do at the crash site?
- #227Which one of the following is correct regarding the engine compartment?
- #228Truck driving is regulated by certain laws, regulations restrictions. Which of the following is true?
About the General Knowledge exam
The General Knowledge knowledge test is a multiple-choice exam administered at every state CDL testing site. The questions on this page are seeded from the AAMVA Commercial Driver License Manual — the same source that state agencies use when writing their official questions — and from the corresponding sections of Title 49 of the Code of Federal Regulations. Real test questions are randomly selected from a much larger pool, so practice covers the rules and concepts rather than the wording of any one item.
The most efficient way to study is to work through this bank twice. The first pass identifies the rules you do not yet know; the second pass confirms recall. Drivers who have studied for years rarely miss a question, but newcomers should expect to need a week or more of repeated reading and quizzing before sitting the real exam. Combine this site with your state's printed CDL handbook for the most complete preparation.