59 General Knowledge Practice Questions & Answers

1. 1. Which three inspections is a CDL driver responsible for performing?

   • A.Pre-trip, during-trip, and after-trip inspection✓ Answer
   • B.Annual, semi-annual, and monthly inspection
   • C.Daily, weekly, and pre-delivery inspection
   • D.Pre-trip, roadside enforcement, and brake-adjustment check

   The manual gives the driver three inspections: before the trip, during the trip (checking tires, brakes, cargo, lights and instruments at stops), and after the trip, when the written inspection report is completed. Annual and roadside inspections are done by mechanics and enforcement officers, not as the driver's own routine.

   Source: AAMVA Model CDL Manual, Vehicle Inspection (three kinds of inspection)Report a problem with this question

2. 2. In the seven-step pre-trip inspection method, what is the first step?

   • A.Turn the lights on and walk around checking every lamp lens
   • B.Start the engine and check the gauges and controls in the cab
   • C.Check the engine compartment fluids while the engine idles
   • D.Do a vehicle overview: last report, leaks, general condition✓ Answer

   Step 1 is the vehicle overview: review the last inspection report, look at the vehicle's general condition, and check the ground for fresh oil, coolant, grease or fuel leaks. The cab check is step 3 and the light walkaround comes later, so starting there skips the leak evidence the overview is designed to catch.

   Source: AAMVA Model CDL Manual, Vehicle Inspection (seven-step method)Report a problem with this question

3. 3. The previous driver's inspection report lists a defect. What must you do?

   • A.Sign the report as received and report the defect again tonight
   • B.Check that it was certified as repaired or as needing no repair✓ Answer
   • C.Repair it yourself before leaving and note the parts used
   • D.Ignore it if the defect did not stop the previous trip

   Federal rules require the motor carrier to certify on the last report that a listed defect was repaired or that no repair was needed, and the driver must review that report and be satisfied of the certification before driving. Simply re-reporting, ignoring, or self-repairing the item does not satisfy the review-and-certification requirement.

   Source: 49 CFR 396.13Report a problem with this question

4. 4. What is the minimum tread depth for tires on a commercial vehicle?

   • A.2/32 inch on steering-axle tires and 4/32 inch on all other tires
   • B.4/32 inch on every tire, including the trailer tires
   • C.4/32 inch on steering-axle tires and 2/32 inch on all others✓ Answer
   • D.2/32 inch on all tires of the tractor and the trailer

   Federal regulation sets a deeper minimum on the steering axle, 4/32 inch, because a steer-tire failure takes away directional control, while 2/32 inch applies to every other wheel position. Reversing the two values is the classic error, and retreads are also barred from the steering axle.

   Source: 49 CFR 393.75Report a problem with this question

5. 5. Which suspension condition is an out-of-service defect?

   • A.A torque rod with fresh paint over an old weld mark
   • B.An air bag inflated below the tire's cold pressure
   • C.A cracked or broken leaf in a leaf-spring assembly✓ Answer
   • D.A spring assembly coated with road dirt and grime

   A cracked, broken, missing or shifted spring leaf is an out-of-service item because the suspension can no longer hold the axle in position under load. Dirt, unrelated air-bag pressure comparisons and cosmetic paint are not defects by themselves, though a repaired weld is worth a closer look.

   Source: 49 CFR 393.207; AAMVA Model CDL Manual, Vehicle InspectionReport a problem with this question

6. 6. What colour must the clearance lights and reflectors on a trailer be?

   • A.Amber at the rear and red at the front and the forward sides
   • B.Red at the rear, the front, and along both sides of the trailer
   • C.Amber at the rear, the front, and both sides of the trailer
   • D.Red at the rear and amber at the front and forward sides✓ Answer

   Lamps and reflectors facing rearward must be red and those facing forward must be amber, so a driver behind you sees red and a driver approaching from the front or front quarter sees amber. Mixing the colours destroys that at-a-glance cue about which end of the trailer is which.

   Source: 49 CFR 393.11Report a problem with this question

7. 7. After the first 50 miles, how often must you re-examine cargo securement?

   • A.Only at the end of the day, when the trip report is written
   • B.Every 3 hours or 150 miles, or at each change of duty status✓ Answer
   • C.Every 2 hours or 100 miles, or at each stop made to buy fuel
   • D.Every 4 hours or 200 miles, or whenever you leave the vehicle

   The rule requires an inspection of the cargo and its securement within the first 50 miles and then a re-examination at whichever comes first of 3 hours, 150 miles, or a change of duty status. Load settling and vibration loosen tie-downs steadily, so the interval is fixed rather than left to the driver.

   Source: 49 CFR 392.9Report a problem with this question

8. 8. When must a retarder be switched off?

   • A.When the road is wet, icy, or covered with snow✓ Answer
   • B.When the engine is still cold at the start of a trip
   • C.When you are towing a loaded trailer up a long grade
   • D.When you are descending a long and very steep grade

   A retarder applies braking force through the drive wheels only, so on a slippery surface it can lock those wheels and start a drive-wheel skid or jackknife. On a dry downgrade it is exactly what you want on, which is why the slippery-road exception is the tested point.

   Source: AAMVA Model CDL Manual, Controlling Your Vehicle (retarders)Report a problem with this question

9. 9. What must you do before you start down a steep downgrade?

   • A.Wait until speed builds, then downshift into a low gear
   • B.Build speed at the crest so you can climb the next hill
   • C.Shift into neutral and coast down to save fuel and brakes
   • D.Shift into a low gear and check the service brakes first✓ Answer

   Gear selection has to happen before gravity takes over, because once speed builds the transmission may refuse to go into any gear and you lose engine braking entirely. Coasting in neutral is both unsafe and unlawful, and waiting to downshift is the mistake that produces runaways.

   Source: AAMVA Model CDL Manual, Mountain DrivingReport a problem with this question

10. 10. When upshifting a manual transmission, what comes right after you shift to neutral?

    • A.Hold the clutch down until the next gear slips in easily
    • B.Press the accelerator to bring the engine speed back up
    • C.Apply the service brake lightly to settle the drivetrain
    • D.Release the clutch and let the engine and gears slow down✓ Answer

    In double-clutching to a higher gear you release the clutch in neutral so engine and gear speeds fall to match the higher gear, then clutch in again and shift. Revving in neutral belongs to downshifting, and riding the clutch through neutral defeats the whole purpose of the technique.

    Source: AAMVA Model CDL Manual, Controlling Your Vehicle (double clutching)Report a problem with this question

11. 11. How should you use your turn signal when making a turn?

    • A.Signal only when another vehicle is close behind you
    • B.Signal early, cancel it just before the turn, then turn
    • C.Signal as you begin the turn and cancel it while turning
    • D.Signal early, keep it on through the turn, then cancel it✓ Answer

    Signalling early gives following and oncoming traffic time to react to a vehicle that turns slowly and swings wide, and keeping the signal on through the turn tells them the manoeuvre is not finished. Cancelling early or signalling late leaves other drivers guessing at the worst moment.

    Source: AAMVA Model CDL Manual, Communicating (signaling turns)Report a problem with this question

12. 12. Why should you back toward the driver's side whenever you can?

    • A.Traffic behind you is required to pass on the right side
    • B.The mirrors on the driver's side are larger and see farther
    • C.The trailer turns more sharply toward the driver's side
    • D.You can see the rear of the vehicle out of the side window✓ Answer

    Backing to the left lets you look directly out of the window at the path instead of relying on a mirror on your blind side, so a mistake is seen and corrected sooner. Mirror size, turning radius and rules about passing have nothing to do with the recommendation.

    Source: AAMVA Model CDL Manual, Controlling Your Vehicle (backing safely)Report a problem with this question

13. 13. What should you do before you begin backing?

    • A.Sound the horn twice and start backing right away
    • B.Set the trailer brakes and back using mirrors only
    • C.Get out and walk around to look at the whole path✓ Answer
    • D.Drive past the space and back in on the blind side

    Get out and look is the rule because mirrors cannot show low obstacles, soft ground, overhead wires or a child directly behind the trailer, and the situation can change while you are parked. Horn signals, mirrors alone, and deliberately choosing the blind side all leave that area unchecked.

    Source: AAMVA Model CDL Manual, Controlling Your Vehicle (backing safely)Report a problem with this question

14. 14. To move the rear of a trailer to the right while backing, you should:

    • A.keep the wheel straight and let the tractor drift to the right
    • B.turn the wheel right, then left as the trailer swings over
    • C.turn the steering wheel to the right and hold it steady
    • D.turn the steering wheel to the left, then follow the trailer✓ Answer

    The trailer pivots about the fifth wheel, so steering left pushes the tractor left and swings the trailer's tail to the right; once it is moving you follow it by turning back the other way. Steering the same direction you want the trailer to go is the reflex that turns a simple back into a jackknife.

    Source: AAMVA Model CDL Manual, Controlling Your Vehicle (backing with a trailer)Report a problem with this question

15. 15. At speeds below 40 mph, what following distance does the manual give?

    • A.One second for every 10 mph of your road speed
    • B.One second for every 10 feet of vehicle length✓ Answer
    • C.One second for every 20 feet of vehicle length
    • D.Two seconds for every 10 feet of vehicle length

    Below 40 mph the manual's rule is one second of following time for each 10 feet of vehicle length, which scales the gap to how long the rig takes to clear a point. Above 40 mph you add one more second, and forgetting that addition is the usual error.

    Source: AAMVA Model CDL Manual, Managing Space (following distance)Report a problem with this question

16. 16. You drive a 60-foot combination at 55 mph. What is the minimum following distance?

    • A.7 seconds, because you add one second above 40 mph✓ Answer
    • B.8 seconds, adding two seconds for highway speeds
    • C.5 seconds, at one second for every 12 feet of length
    • D.6 seconds, because only vehicle length sets the figure

    Sixty feet of length gives six seconds at one second per ten feet, and because 55 mph is above 40 mph you add one second for a total of seven. Stopping at six is the common slip, and inventing a twelve-foot or two-second variation is not the manual's rule.

    Source: AAMVA Model CDL Manual, Managing Space (following distance)Report a problem with this question

17. 17. A car is following you too closely. What should you do?

    • A.Move into the left lane so that the car can go by on the right
    • B.Flash the brake lights a few times to warn the driver to drop back
    • C.Speed up gradually to open the gap behind your trailer again
    • D.Stay to the right, hold a steady speed, and let the driver pass✓ Answer

    You cannot control the space behind you, so the safe response is to make passing easy: stay right, keep your speed steady and avoid sudden moves. Speeding up only moves the tailgater along at a higher speed, and flashing the brakes invites the rear-end crash you are trying to avoid.

    Source: AAMVA Model CDL Manual, Managing Space (space behind)Report a problem with this question

18. 18. Total stopping distance for a vehicle without air brakes is made up of:

    • A.perception distance, reaction distance, and braking distance✓ Answer
    • B.reaction distance, skid distance, and the length of the vehicle
    • C.perception distance, braking distance, and coasting distance
    • D.reaction distance, braking distance, and brake lag distance

    Perception distance covers the travel while you recognise the hazard, reaction distance the travel while you move your foot, and braking distance the travel after the brakes take hold. Brake lag is a fourth component added only for air brakes, and conflating the two totals is a frequent error.

    Source: AAMVA Model CDL Manual, Controlling Speed (stopping distance)Report a problem with this question

19. 19. At 55 mph on dry pavement, how far does a truck travel from seeing a hazard to stopping?

    • A.About 61 feet, which is the reaction distance
    • B.About 142 feet, which is the perception distance
    • C.About 419 feet, longer than a football field✓ Answer
    • D.About 216 feet, which is the braking distance

    At 55 mph the manual adds roughly 142 feet of perception, 61 feet of reaction and 216 feet of braking for about 419 feet in total, and each wrong option is one of those parts quoted as if it were the whole. With air brakes you add about 32 feet of lag, giving over 450 feet.

    Source: AAMVA Model CDL Manual, Controlling Speed (stopping distance)Report a problem with this question

20. 20. Going from 20 mph to 40 mph does what to braking distance and force of impact?

    • A.It multiplies both of them by about three
    • B.It multiplies both of them by about four✓ Answer
    • C.It multiplies both of them by about two
    • D.It multiplies both of them by about nine

    Braking distance and impact energy rise with the square of speed, so doubling the speed multiplies both by four rather than two. Tripling from 20 to 60 mph multiplies them by nine, which is why small speed reductions matter so much on a heavy vehicle.

    Source: AAMVA Model CDL Manual, Controlling Speed (speed and stopping distance)Report a problem with this question

21. 21. Why can an empty truck need a longer stopping distance than a loaded one?

    • A.Less weight gives the tires and brakes less traction to use✓ Answer
    • B.Brake linings grip a cold, unloaded drum far more strongly
    • C.An empty trailer puts more weight on the steering tires
    • D.Empty trucks are always driven at a higher road speed

    Brakes and tires are designed to work best at the vehicle's loaded weight, so an empty rig has less traction, the wheels lock more easily, and the truck can bounce and skid instead of stopping. Assuming the lighter vehicle always stops sooner is the classic reversed answer.

    Source: AAMVA Model CDL Manual, Controlling Speed (empty trucks)Report a problem with this question

22. 22. How much should you reduce speed on a wet road and on packed snow?

    • A.By about a quarter when wet and a third on packed snow
    • B.By about a third when wet and a quarter on packed snow
    • C.By about a half when wet and by a third on packed snow
    • D.By about a third when wet and by a half on packed snow✓ Answer

    The manual's guidance is to cut speed by about one-third on a wet road, for example from 55 to roughly 35 mph, by one-half or more on packed snow, and to a crawl on ice. Swapping the two fractions leaves far too much speed for the surface with the least traction.

    Source: AAMVA Model CDL Manual, Controlling Speed (slippery surfaces)Report a problem with this question

23. 23. When can hydroplaning start, and what should you do if it happens?

    • A.As low as 30 mph in 1/10 inch of water; release the accelerator✓ Answer
    • B.Only above 50 mph in deep standing water; brake firmly at once
    • C.As low as 30 mph in 1/10 inch of water; brake hard to slow down
    • D.Only above 40 mph in 1/4 inch of water; steer sharply to one side

    Hydroplaning can begin at about 30 mph with as little as one-tenth of an inch of water, and because the tires have lost contact with the road the cure is to release the accelerator and push in the clutch so the vehicle slows itself. Braking or steering sharply while the tires are riding on water only provokes a skid.

    Source: AAMVA Model CDL Manual, Controlling Speed (hydroplaning)Report a problem with this question

24. 24. What is an escape ramp for?

    • A.To let an overheated engine cool before the next long climb
    • B.To stop a runaway vehicle safely in a bed of loose material✓ Answer
    • C.To give slow trucks a place to let faster traffic get past
    • D.To provide a legal spot for the required brake-check stop

    Escape ramps are built beside steep downgrades with a long bed of loose gravel or sand, sometimes on an upgrade, so a vehicle whose brakes have failed or faded can be stopped without injuring the driver or others. Knowing where they are on your route is part of planning a mountain descent.

    Source: AAMVA Model CDL Manual, Mountain Driving (escape ramps)Report a problem with this question

25. 25. Which statement about overhead clearance is true?

    • A.Posted clearance signs are always legally accurate
    • B.An empty trailer rides higher than a loaded one✓ Answer
    • C.Trailer height does not change with the load weight
    • D.A loaded trailer rides higher than an empty one

    Weight compresses the suspension and tires, so an empty trailer sits higher and can strike an overpass that it cleared while loaded. Posted heights can also be wrong after repaving or under packed snow, which is why the sign alone is never proof that you will fit.

    Source: AAMVA Model CDL Manual, Managing Space (overhead clearance)Report a problem with this question

26. 26. What do convex (spot) mirrors do to what you see?

    • A.They show a wider area, but things look smaller and farther away✓ Answer
    • B.They show a wider area, and things look larger and closer in
    • C.They show a narrower area, and things look their true size
    • D.They show a wider area, and distances stay exactly correct

    A curved mirror surface squeezes a wide field into a small glass, which is why it covers blind spots but makes every vehicle look smaller and therefore farther away than it is. Judging a gap from the convex mirror alone is how drivers pull out in front of traffic that is much closer than it looked.

    Source: AAMVA Model CDL Manual, Seeing (mirror use)Report a problem with this question

27. 27. How far ahead should you be looking while driving?

    • A.4 to 6 seconds, roughly one city block at highway speed
    • B.12 to 15 seconds, about a quarter mile at highway speed✓ Answer
    • C.20 to 25 seconds, about half a mile at highway speed
    • D.8 to 10 seconds, roughly 200 feet at highway speed

    Looking 12 to 15 seconds ahead, roughly one block in the city and a quarter mile on the highway, gives a heavy vehicle time to slow or change lanes smoothly instead of braking hard. A shorter scan leaves no room for a rig that needs hundreds of feet to stop.

    Source: AAMVA Model CDL Manual, Seeing (looking ahead)Report a problem with this question

28. 28. Stopped on the shoulder of a two-lane, two-way road, where do the warning devices go?

    • A.10 feet on the traffic side, 100 feet behind, 200 feet behind
    • B.10 feet on the traffic side, 100 feet behind, 100 feet ahead✓ Answer
    • C.10 feet behind, 200 feet behind, and 300 feet ahead of the truck
    • D.50 feet on the traffic side, 100 feet behind, 150 feet ahead

    On an undivided two-way road traffic comes from both directions, so the devices go 10 feet to the traffic side of the vehicle, 100 feet behind and 100 feet ahead, all within 10 minutes of stopping. The 10, 100 and 200 foot pattern applies instead on a one-way or divided highway.

    Source: 49 CFR 392.22Report a problem with this question

29. 29. A hazard is any road condition or road user that could become a danger. According to the model CDL manual, what turns a hazard into an emergency?

    • A.You spot it so late that there is no room or time to react smoothly✓ Answer
    • B.Another driver breaks a traffic law, which by itself creates an emergency
    • C.You have to use the service brakes firmly instead of just easing off fuel
    • D.The hazard is a fixed object rather than a moving vehicle or a pedestrian

    The manual treats an emergency as a hazard recognized too late: once the remaining space and time are too small for a gradual adjustment, the driver is forced into a sudden move. Spotting hazards far ahead is what keeps them from ever becoming emergencies.

    Source: AAMVA Model CDL Manual, Seeing Hazards / Driving EmergenciesReport a problem with this question

30. 30. It has been raining and the temperature is just above freezing. Which part of your route is most likely to ice over first?

    • A.Uphill grades, where slow traffic packs moisture into the road
    • B.Long open straights in the sun, where wind cools the pavement
    • C.Newly paved sections, where fresh asphalt holds the least heat
    • D.Bridges and overpasses, which lose heat from above and below✓ Answer

    A bridge deck has cold air flowing under it as well as over it, so it cannot draw heat from the ground the way ordinary pavement does and it freezes while the road on either side is still only wet. Shaded spots ice early for the same reason.

    Source: AAMVA Model CDL Manual, Speed Management — slippery surfacesReport a problem with this question

31. 31. Driving through standing water, your steering suddenly feels light and the vehicle does not answer the wheel. What should you do?

    • A.Apply the brakes steadily to force the tires back down on the road
    • B.Steer firmly toward the shoulder to reach a drier strip of surface
    • C.Accelerate gently so the tires cut through the film of water ahead
    • D.Release the accelerator, push in the clutch, and let the vehicle slow✓ Answer

    Light steering in standing water means the tires are hydroplaning on a wedge of water and have lost contact with the pavement. Braking or hard steering does nothing while the tires are not touching the road and invites a skid once they grab, so the manual says to release the accelerator and declutch until the wheels slow.

    Source: AAMVA Model CDL Manual, Speed Management — hydroplaningReport a problem with this question

32. 32. You must keep driving in dense fog. Which lights should you use?

    • A.High beams, which reach farther down the roadway
    • B.Clearance lights only, to cut the glare back at you
    • C.Low beams, plus fog lights if the vehicle has them✓ Answer
    • D.Four-way flashers alone, so other drivers see you

    Fog is made of water droplets that scatter light straight back at the driver, so a high beam aimed into it produces a wall of glare and shortens the distance you can see. Low beams and fog lights throw light under the fog layer instead.

    Source: AAMVA Model CDL Manual, Driving in FogReport a problem with this question

33. 33. You are approaching a long, steep downgrade. When should you select the low gear you will use on the grade?

    • A.Before you start down, while still level at the top✓ Answer
    • B.When your speed reaches the limit and the brakes get hot
    • C.At the first sharp curve, so the gear suits that curve
    • D.After the grade begins, once you feel the load pushing

    Gravity builds speed fast on a grade, and a modern transmission will refuse a downshift once engine rpm is too high, which can leave a driver with no gear at all partway down. Choosing the low gear on the level at the top avoids that.

    Source: AAMVA Model CDL Manual, Mountain DrivingReport a problem with this question

34. 34. On a hot day you stop to check the tires and find one too hot to touch, reading far above the pressure you set that morning. What should you do?

    • A.Bleed off air until the gauge reads the morning setting
    • B.Drive on slowly, because heat always raises tire pressure
    • C.Stop driving and let the tire cool before going on again✓ Answer
    • D.Cool the tire with water and re-check it in ten minutes

    A tire too hot to touch is on its way to a blowout, and the high reading is normal thermal expansion, not overinflation. Letting air out leaves the tire underinflated once it cools, which generates still more heat, so the manual says to stop until the tire cools.

    Source: AAMVA Model CDL Manual, Hot Weather DrivingReport a problem with this question

35. 35. Which vehicles must stop at every public railroad crossing, 15 to 50 feet before the nearest rail?

    • A.Every vehicle that requires a Class A commercial driver license
    • B.Buses carrying passengers and vehicles displaying hazmat placards✓ Answer
    • C.Any truck whose load sits lower than 12 inches above the roadway
    • D.Any combination vehicle measuring more than 60 feet from end to end

    The mandatory-stop rule is written around what the vehicle carries, not how big it is: buses with riders and placarded hazmat vehicles must stop, look and listen, then cross without shifting. Length and license class do not by themselves create a stop requirement.

    Source: 49 CFR 392.10; AAMVA Model CDL Manual, Railroad-Highway CrossingsReport a problem with this question

36. 36. Traffic is backed up on the far side of a railroad crossing and you are not sure there is room for your whole vehicle beyond the tracks. What should you do?

    • A.Cross in a low gear and shift up once the trailer is clear
    • B.Wait behind the crossing until there is room to clear it fully✓ Answer
    • C.Move onto the tracks and stop, then go ahead as space opens
    • D.Start across and sound the horn so the traffic ahead moves up

    Federal rules forbid starting across a track unless the vehicle can get completely clear without stopping, because a rig stopped on the rails cannot be moved fast enough when a train appears. A tractor-trailer needs roughly fourteen seconds to clear a single track.

    Source: 49 CFR 392.12; AAMVA Model CDL Manual, Railroad-Highway CrossingsReport a problem with this question

37. 37. Your service brakes have faded to nothing on a long mountain downgrade, and a sign shows an escape ramp one mile ahead. What is the correct action?

    • A.Pass the ramp and scrub off speed against the guardrail instead
    • B.Take the escape ramp, even though the vehicle will be damaged✓ Answer
    • C.Pass the ramp and drift onto the gravel shoulder to slow down
    • D.Pump the brake pedal hard to rebuild pressure before the ramp

    Escape ramps exist precisely for a runaway on a grade; they stop the vehicle with sand or gravel and cause only minor damage, while a runaway that passes one keeps accelerating. Pumping an air brake pedal wastes the little air left rather than rebuilding pressure.

    Source: AAMVA Model CDL Manual, Driving Emergencies — brake failureReport a problem with this question

38. 38. You hear a loud bang and the steering immediately becomes very hard to turn. What has most likely happened, and what should you do?

    • A.A front tire has blown; grip the wheel firmly and stay off the brake✓ Answer
    • B.A drive axle has locked up; downshift quickly to free the wheels
    • C.The power steering has failed; brake hard and pull to the shoulder
    • D.A rear tire has blown; brake at once to keep the trailer in line

    A steer-tire failure shows up as sudden heavy steering and a pull to that side, and braking then transfers weight onto the collapsed tire and can pull the vehicle across a lane. Holding the wheel and letting the rig slow itself keeps it straight until it is slow enough to brake gently.

    Source: AAMVA Model CDL Manual, Driving Emergencies — tire failureReport a problem with this question

39. 39. Your rear drive wheels lock up and the trailer starts to swing out to one side. What is the first thing you should do?

    • A.Release the brakes so the rear wheels can roll and grip again✓ Answer
    • B.Press harder on the brake pedal to pull the trailer back in line
    • C.Apply the trailer hand valve to drag the trailer straight again
    • D.Shift into a lower gear so engine braking pulls the rig straight

    A trailer jackknife is a drive-wheel skid: locked wheels have no side grip, so the trailer pushes them sideways. Only rolling wheels can grip again, so the recovery begins with releasing the brakes, then countersteering as the rig straightens.

    Source: AAMVA Model CDL Manual, Skid Control and RecoveryReport a problem with this question

40. 40. In a front-wheel skid the vehicle keeps going straight no matter how far you turn the steering wheel. What is the only way to end it?

    • A.Brake with firm steady pressure to make the front tires bite
    • B.Turn the wheel farther toward where you want the vehicle to go
    • C.Slow down: stop braking and accelerating until traction returns✓ Answer
    • D.Speed up briefly to shift weight forward onto the steering axle

    In a front-wheel skid the steering tires have already exceeded the grip available, so any further steering input, braking or acceleration only asks for more grip that is not there. Speed is the one variable the driver can still reduce, and traction returns as it falls.

    Source: AAMVA Model CDL Manual, Skid Control and RecoveryReport a problem with this question

41. 41. A car ahead of you stops suddenly and you may not have room to stop in time. What does the manual say about stopping versus steering?

    • A.Steering away is usually quicker, since turning needs less distance✓ Answer
    • B.Steering is safer only at speeds below about 20 miles per hour
    • C.Stopping is always safer, because a turn can roll a loaded vehicle
    • D.Stopping is quicker, because air brakes act faster than a steer move

    The manual states that a vehicle can change direction in less distance than it can stop, so steering around an obstacle is usually the faster escape. The limit is rollover: the steering move must be smooth, and the driver must countersteer once past the hazard.

    Source: AAMVA Model CDL Manual, Driving EmergenciesReport a problem with this question

42. 42. Your truck carries a B:C rated fire extinguisher. Which fire is that rating meant for?

    • A.Cardboard cartons burning in the middle of the load
    • B.Cotton bales burning on the deck of a flatbed trailer
    • C.Wood pallets burning at the rear of the box trailer
    • D.Spilled diesel burning under the engine of the tractor✓ Answer

    Class B covers burning liquids such as diesel, gasoline and grease, and Class C covers energized electrical fires; a B:C unit is rated for both. Wood, paper, cloth and cardboard are Class A materials and need an extinguisher whose rating begins with A.

    Source: AAMVA Model CDL Manual, Accident Procedures and Fires; 49 CFR 393.95Report a problem with this question

43. 43. You are about to use a fire extinguisher on a cargo fire. How should you position yourself and aim?

    • A.Stand beside the flames at arm's length, sweeping the middle
    • B.Stay downwind and close in, aiming at the top of the flames
    • C.Stand upwind but very close, aiming above the flames to smother
    • D.Stay upwind, as far back as it reaches, aiming at the base✓ Answer

    Standing upwind keeps flame, smoke and toxic fumes blowing away from the operator, and the extinguisher is designed to be used from the far end of its range. Aiming at the base attacks the burning fuel itself; spraying the visible flame above it accomplishes nothing.

    Source: AAMVA Model CDL Manual, Fighting FiresReport a problem with this question

44. 44. Smoke is coming from the rear of your loaded van trailer. What should you do?

    • A.Drive to the next exit so the wind clears the smoke
    • B.Keep the doors shut and wait for the fire department✓ Answer
    • C.Open the doors at once to find out what is burning
    • D.Open one door a crack and spray the extinguisher in

    A cargo fire inside a closed van is starved of oxygen, and opening the doors feeds it air so it flares up in the driver's face. The manual tells drivers to leave a burning van trailer shut and let trained firefighters open it.

    Source: AAMVA Model CDL Manual, Fighting FiresReport a problem with this question

45. 45. You are stopped on the shoulder of a divided highway. Where do your three reflective triangles go?

    • A.At 10 feet, 200 feet and 300 feet ahead of the stopped truck
    • B.At 10 feet and 100 feet, one on each side of the stopped truck
    • C.At 50 feet, 200 feet and 500 feet toward approaching traffic
    • D.At 10 feet, 100 feet and 200 feet toward approaching traffic✓ Answer

    On a one-way or divided highway all three devices go back toward approaching traffic at 10, 100 and 200 feet, because traffic can only reach the vehicle from one direction. The two-way undivided pattern is different: one device ahead and one behind.

    Source: 49 CFR 392.22; AAMVA Model CDL Manual, CommunicatingReport a problem with this question

46. 46. You are the first to arrive at a crash scene. In what order should you take the three basic steps?

    • A.Notify the authorities, care for the injured, then protect the area
    • B.Protect the area, notify the authorities, then care for the injured✓ Answer
    • C.Protect the area, care for the injured, then notify the authorities
    • D.Care for the injured, protect the area, then notify the authorities

    Protecting the area comes first because a second collision into the scene would add victims, including the helper. Notification comes next so that trained help is already on its way while the driver, who is usually not a medic, gives what care he can.

    Source: AAMVA Model CDL Manual, Accident ProceduresReport a problem with this question

47. 47. What does Gross Vehicle Weight Rating (GVWR) mean?

    • A.The maximum a single vehicle plus its load is rated to weigh✓ Answer
    • B.The maximum weight one axle of the vehicle may legally carry
    • C.The maximum a power unit plus its towed unit is rated to weigh
    • D.The actual weight of a single vehicle plus the load it carries

    GVWR is a rating set by the manufacturer for one vehicle and it does not change with the load, which is what separates it from GVW, the weight actually on the scale. The combination equivalents are GCW and GCWR.

    Source: 49 CFR 383.5; AAMVA Model CDL Manual, Transporting Cargo SafelyReport a problem with this question

48. 48. Two trucks carry the same load on the same number of axles, but one has that axle group spaced closer together. How does the federal bridge formula treat it?

    • A.The group with the closer spacing is allowed more total weight
    • B.Spacing below 40 feet is ignored, so both are treated alike
    • C.The group with the closer spacing is allowed less total weight✓ Answer
    • D.Both groups are allowed the same weight; only axle count counts

    The bridge formula limits weight by how far it is spread out, because axles bunched together concentrate the load on a short span of bridge deck. Spreading the same axles farther apart raises the legal allowance for that group.

    Source: Federal Bridge Formula, 23 U.S.C. 127; AAMVA Model CDL Manual, Transporting Cargo SafelyReport a problem with this question

49. 49. You are loading boxed freight of mixed weights into a van trailer. How should it be arranged?

    • A.Heavy items low and spread along the length, light ones on top✓ Answer
    • B.Heavy items all in the nose, light ones filling the rear half
    • C.Heavy items high and toward the rear, light ones low in front
    • D.Heavy items against the rear doors, light ones toward the nose

    Weight carried high raises the center of gravity and makes a rollover likely in a curve or a quick lane change, while bunching it at one end overloads either the steering axle or the rear tandem. Low and evenly spread keeps the vehicle stable and legal on each axle.

    Source: AAMVA Model CDL Manual, Transporting Cargo Safely — balancing the weightReport a problem with this question

50. 50. The aggregate working load limit of the tiedowns must equal at least how much of the weight of the cargo being secured?

    • A.At least the full weight of the article being secured
    • B.At least a quarter of the weight of the article secured
    • C.At least half the weight of the article being secured✓ Answer
    • D.At least twice the weight of the article being secured

    Federal securement rules set the aggregate working load limit of the whole system at one half the weight of the articles secured, on the reasoning that friction and blocking carry part of the load. Working load limit is itself a fraction of breaking strength, so the real margin is larger than it sounds.

    Source: 49 CFR 393.106; AAMVA Model CDL Manual, Transporting Cargo SafelyReport a problem with this question

51. 51. After beginning a trip, when must a driver first stop to re-examine the cargo and its securing devices?

    • A.After the first 150 miles of the trip
    • B.After the first 3 hours of driving time
    • C.Within the first 50 miles of the trip✓ Answer
    • D.Within the first 25 miles of the trip

    Straps and chains settle and loosen most in the first miles as the load shifts into place, so the rule requires an inspection within the first 50 miles. After that the cargo must be rechecked every 3 hours or 150 miles or at each break, whichever comes first.

    Source: 49 CFR 392.9; AAMVA Model CDL Manual, Inspecting CargoReport a problem with this question

52. 52. Which statement about alcohol and commercial driving is correct under the federal rules?

    • A.At .08 percent or more in a CMV, the CDL is lost for at least a year
    • B.At .04 percent or more in a CMV, the CDL is lost for at least a year✓ Answer
    • C.Below .04 percent, a driver with alcohol present may keep on driving
    • D.At .02 percent or more in a CMV, the CDL is lost for at least a year

    The commercial limit is half the usual car limit: .04 percent is the level at which operating a CMV is a first offense costing the CDL for a minimum of one year, or three years if the vehicle was placarded for hazardous materials. Any detectable alcohol at .02 percent or above puts the driver out of service for 24 hours even though it is below .04.

    Source: 49 CFR 383.51 and 392.5; AAMVA Model CDL Manual, Driver DisqualificationsReport a problem with this question

53. 53. A driver stopped while operating a CMV refuses to take the required alcohol test. What is the consequence?

    • A.The CDL is suspended 24 hours and the driver may then continue
    • B.The CDL is lost for 60 days, the same as two serious violations
    • C.The CDL is lost for at least a year, as if the test had been failed✓ Answer
    • D.The driver is fined but keeps the CDL unless convicted in court

    Holding a CDL is implied consent to testing, so refusal is treated exactly like a failed test and carries the same first-offense disqualification of one year, or three years in a placarded hazmat vehicle. Refusing therefore gains the driver nothing.

    Source: 49 CFR 383.51; AAMVA Model CDL Manual, Driver DisqualificationsReport a problem with this question

54. 54. Under the federal hours-of-service rules for property-carrying drivers, when must a 30-minute break be taken?

    • A.After 11 cumulative hours of driving inside the 14-hour window
    • B.After 8 consecutive hours on duty, whether driving or not
    • C.After 8 cumulative hours of driving time without such a break✓ Answer
    • D.After 6 cumulative hours of driving, at the middle of the shift

    The break is keyed to driving time, not to time on duty: after 8 cumulative hours behind the wheel a driver needs at least 30 consecutive minutes of non-driving time before driving again. The 11-hour figure is the daily driving cap, not the break trigger.

    Source: 49 CFR 395.3(a)(3)(ii)Report a problem with this question

55. 55. A tractor rated 20,000 pounds GVWR tows a trailer rated 15,000 pounds GVWR, for a combination rated 35,000 pounds. Which class of CDL is required?

    • A.Class B, because the power unit alone is under 26,001 pounds
    • B.No CDL, because the trailer is not rated over 20,000 pounds
    • C.Class A, because the towed unit is rated over 10,000 pounds✓ Answer
    • D.Class C, because neither unit by itself reaches 26,001 pounds

    Class A applies when the combination is rated 26,001 pounds or more and the unit or units being towed are rated over 10,000 pounds. Here 35,000 clears the combination threshold and the 15,000-pound trailer clears the towed-unit threshold, so neither unit needs to reach 26,001 on its own.

    Source: 49 CFR 383.91; AAMVA Model CDL Manual, Commercial Driver License TestsReport a problem with this question

56. 56. You hold a Class B CDL with no endorsements and no restrictions. Which vehicle may you legally drive?

    • A.A 30,000-pound dump truck placarded for 2,000 pounds of oxidizer
    • B.A 30,000-pound tank truck holding 2,000 gallons of milk in one tank
    • C.A 30,000-pound box truck with hazardous materials but no placards✓ Answer
    • D.A 30,000-pound transit bus built to seat 40 riders plus the driver

    Hazardous materials in quantities that do not require placards may be hauled on a plain CDL, so only that load is open to a driver with no endorsements. The milk tank needs N because the tank exceeds 119 gallons individually and 1,000 in total even though milk is not hazardous, the bus needs P, and the placarded dump truck needs H.

    Source: 49 CFR 383.93; AAMVA Model CDL Manual, Commercial Driver License TestsReport a problem with this question

57. 57. During a pre-trip inspection of a truck with hydraulic brakes, how do you check the system for leaks?

    • A.Pump the pedal three times, then hold firm pressure on it for a full five seconds✓ Answer
    • B.Press the pedal once and hold it lightly while the engine idles for a minute
    • C.Roll forward at five miles per hour and apply the pedal hard to feel pulling
    • D.Start the engine and pump the pedal ten times, listening for the warning buzzer

    Pumping the pedal three times bleeds off the vacuum or power-assist reserve, so the next firm application tests the hydraulic circuit by itself. If the pedal sinks at all during the five seconds you hold it, fluid is escaping past a seal or through a leaking line and the vehicle must not be driven.

    Source: AAMVA Model Commercial Driver License Manual, Vehicle Inspection — hydraulic brake checkReport a problem with this question

58. 58. You have just driven through water deep enough to soak your brakes. What should you do to get them working normally again?

    • A.Pull onto the shoulder and let the brakes air-dry for several minutes before going on
    • B.Drive slowly in a low gear, pressing the brakes lightly while applying engine power✓ Answer
    • C.Speed up briefly so airflow through the wheels blows the water off the brake linings
    • D.Set the parking brake for a minute, then release it and continue at normal speed

    Wet linings and drums can leave the brakes weak, make them grab, or make them pull to one side. Driving in a low gear with light pedal pressure against engine power keeps the shoes rubbing the drums, and that friction heat drives the water off; parking or accelerating produces no such heat.

    Source: AAMVA Model Commercial Driver License Manual, Driving in Winter — wet brakesReport a problem with this question

59. 59. On your day off you are convicted of speeding in your own car. What does the federal rule require of you as a CDL holder?

    • A.Report it to your employer only if the violation happened in a commercial vehicle
    • B.Report the conviction to your employer at your next annual driving-record review
    • C.Report the conviction to your employer within thirty days, whatever vehicle you drove✓ Answer
    • D.Report nothing, since off-duty convictions in a personal car are exempt from notice

    The notification duty attaches to the driver, not to the truck: a CDL holder convicted of any traffic violation other than parking, in any type of motor vehicle and whether on duty or not, must notify the employer in writing within thirty days, and must also notify the licensing state when the conviction happens out of state.

    Source: 49 CFR 383.31 (notification of convictions for driver violations)Report a problem with this question

Practice questions based on the AAMVA/FMCSA model CDL manual. Requirements vary by state — study your state's official CDL manual before your exam. Official CDL info →