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Oklahoma CDL General Knowledge study materials
Oklahoma CDL General Knowledge study resources

Oklahoma CDL General Knowledge practice questions

One question at a time. Build your Oklahoma CDL General Knowledge understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

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Question 1Driving Safely

You are driving a tractor-trailer on a two-lane road at night and an oncoming vehicle's high beams are blinding you. What is the safest response?

  1. Flash your high beams repeatedly to warn the other driver
  2. Turn on your high beams so you can see past the glare
  3. Speed up to pass the oncoming vehicle more quickly
  4. Look toward the right edge of your lane and slow down Correct answer.

Explanation

When oncoming high beams cause glare, you should avoid staring at the lights, look toward the right edge of your lane to stay positioned, and reduce speed until your vision recovers. This keeps you from drifting left into oncoming traffic.

Question 2Driving Safely

Under Oklahoma law and CDL rules, when must a driver of a commercial motor vehicle use seat belts?

  1. Only during nighttime driving hours
  2. Only when traveling on interstate highways
  3. At all times the vehicle is in motion Correct answer.
  4. Only when a passenger is on board

Explanation

CMV drivers must wear a seat belt whenever the vehicle is operating, regardless of road type, time of day, or whether passengers are present. Seat belts are the single most effective protection in a crash.

Question 3Driving Safely

What is the proper way to hold the steering wheel for maximum control of a large commercial vehicle?

  1. One hand at the top of the wheel at all times
  2. Both hands, placed at the 9 and 3 o'clock positions Correct answer.
  3. Both hands gripping the bottom of the wheel
  4. Palms open with fingers laced through the spokes

Explanation

Holding the wheel with both hands at roughly the 9 and 3 o'clock positions gives the best control and keeps your arms clear of the airbag. It also lets you make smooth, precise steering corrections.

Question 4Driving Safely

You are driving a loaded tractor-trailer and need to stop. Compared with a passenger car, your stopping distance will be:

  1. Much longer, requiring more following distance Correct answer.
  2. Shorter because the truck sits higher
  3. Shorter because the trailer brakes help
  4. About the same at any speed

Explanation

A fully loaded CMV weighs far more than a car, so its momentum carries it much farther before it can stop. Drivers must maintain a longer following distance to allow for the increased stopping distance.

Question 5Driving Safely

In Oklahoma, what does a flashing yellow traffic signal mean for a CMV driver?

  1. Yield only to trucks
  2. Proceed with caution Correct answer.
  3. Stop completely before proceeding
  4. Speed up to clear the intersection

Explanation

A flashing yellow signal means slow down and proceed with caution, watching for other traffic and hazards. It does not require a full stop unless conditions or other signs dictate one.

Question 6Driving Safely

When driving a commercial vehicle, what is the recommended minimum following distance under ideal conditions?

  1. One second for each 10 feet of vehicle length Correct answer.
  2. A fixed gap of 50 feet at all speeds
  3. One second total behind the vehicle ahead
  4. Two car lengths regardless of speed

Explanation

The rule of thumb is at least one second of following distance for each 10 feet of vehicle length at speeds under 40 mph, adding a second above 40 mph. This gives the driver time to react and stop.

Question 7Driving Safely

What should you do if your vehicle's brakes fail while you are driving downhill?

  1. Pump the brakes and use a lower gear or escape ramp Correct answer.
  2. Turn off the engine immediately
  3. Steer into the median to slow down
  4. Shift to neutral and coast to a stop

Explanation

If brakes fail, pump the brake pedal to build pressure, downshift to use engine braking, and look for a runaway truck ramp or other safe escape route. Turning off the engine or coasting in neutral removes control you need.

Question 8Driving Safely

You are approaching a railroad crossing with a lowered gate and flashing red lights. What must you do?

  1. Drive around the gate if no train is visible
  2. Proceed slowly under the gate
  3. Stop and wait until the gate rises and lights stop Correct answer.
  4. Sound your horn and cross quickly

Explanation

A lowered gate and flashing red lights require a complete stop until the signals stop and the gate fully rises. Never drive around or under a gate, because a train may be approaching faster than it appears.

Question 9Driving Safely

When must a commercial driver use the vehicle's four-way flashers while driving?

  1. Whenever driving below the posted speed limit
  2. When the vehicle is a hazard, such as moving slowly on a grade Correct answer.
  3. Only during rain or snow
  4. Only when parked on a shoulder

Explanation

Four-way flashers warn other drivers when your vehicle creates a hazard, such as traveling far below the normal speed of traffic or moving slowly up a steep grade. They are not a substitute for turn signals.

Question 10Driving Safely

What is the correct procedure for backing a large commercial vehicle?

  1. Rely on mirrors only and back quickly
  2. Use a helper or get out and check, and back slowly Correct answer.
  3. Sound the horn and back at normal speed
  4. Back without checking if the area looks clear

Explanation

Backing is one of the most dangerous maneuvers for a CMV. Use a spotter when possible, check the area yourself before backing, and move slowly so you can stop if a hazard appears.

Question 11Driving Safely

You are driving in fog. Which lights should you use?

  1. Four-way flashers while moving
  2. High beams for maximum visibility
  3. Parking lights only
  4. Low beams, or fog lights if equipped Correct answer.

Explanation

In fog, use low beams because high beams reflect off the moisture and reduce visibility. Slow down and increase your following distance as well.

Question 12Driving Safely

What does the term 'space cushion' mean in commercial driving?

  1. The load space behind the cab
  2. The clear distance kept around your vehicle Correct answer.
  3. The gap between the tractor and trailer
  4. The padding inside the cab for driver comfort

Explanation

A space cushion is the clear area you maintain around your vehicle on all sides so you have room to react and stop. It includes following distance, lane position, and awareness of vehicles beside you.

Question 13Driving Safely

How should a CMV driver handle a curve on a downgrade?

  1. Brake hard while turning through the curve
  2. Shift to neutral and coast around the curve
  3. Slow down before the curve and use a safe gear Correct answer.
  4. Accelerate through the curve to maintain momentum

Explanation

Reduce speed before entering the curve, then use a gear that lets you maintain control without heavy braking. Braking hard in a curve or coasting in neutral can cause a loss of control or brake fade.

Question 14Driving Safely

What is the purpose of a pre-trip inspection?

  1. To confirm the load weight at a scale
  2. To satisfy paperwork requirements only
  3. To check only the tires and lights
  4. To find defects before they cause a breakdown or crash Correct answer.

Explanation

A pre-trip inspection is a safety check to find problems such as brake, tire, or light defects before you drive. Catching defects early prevents breakdowns and crashes and is required by federal and state rules.

Question 15Driving Safely

You are driving a tanker vehicle and feel the load shifting as you take a curve. What should you do?

  1. Steer smoothly and reduce speed gradually Correct answer.
  2. Brake firmly to stabilize the load
  3. Accelerate to shift the liquid to the rear
  4. Turn sharply to correct the vehicle's path

Explanation

Liquid loads shift and can cause a rollover if you brake or steer abruptly. Ease off the accelerator, steer smoothly, and reduce speed gradually to keep the vehicle stable.

Question 16Driving Safely

What does a solid white line at the right edge of the roadway indicate?

  1. The center of a two-way road
  2. The right edge of the travel lane Correct answer.
  3. A no-parking zone
  4. A lane reserved for passing

Explanation

A solid white line at the right edge marks the right boundary of the travel lane. It helps drivers keep their vehicle positioned, especially at night or in bad weather.

Question 17Driving Safely

When a school bus has its red lights flashing and stop arm extended on a two-lane road, what must a CMV driver do?

  1. Slow down and pass carefully
  2. Change lanes and continue at speed
  3. Honk and proceed if children are not visible
  4. Stop until the red lights stop flashing Correct answer.

Explanation

On an undivided two-lane road, traffic in both directions must stop for a school bus with flashing red lights and its stop arm out. You may proceed only after the lights stop and the arm retracts.

Question 18Driving Safely

A commercial driver is about to drive after taking a prescription medication that causes drowsiness. What is the correct action?

  1. Drive only on local roads
  2. Take a second dose to build tolerance
  3. Drive with the windows down for alertness
  4. Do not drive until cleared by a medical professional Correct answer.

Explanation

Driving while impaired by any substance, including a drowsiness-causing medication, is unsafe and prohibited. Consult the prescribing professional and do not drive until you know the medication will not impair you.

Question 19Driving Safely

What is the effect of 'brake fade' on a long downgrade?

  1. The trailer brakes apply harder than the tractor
  2. Brakes become more responsive as they heat
  3. Brakes lose effectiveness from overheating Correct answer.
  4. The parking brake engages automatically

Explanation

Continuous braking on a long downgrade overheats the brakes and causes fade, meaning they lose stopping power. Use a lower gear and controlled braking to avoid overheating.

Question 20Driving Safely

You are driving a CMV with air brakes and the low air pressure warning comes on. What should you do?

  1. Pump the brakes to build pressure while driving
  2. Ignore it if the brakes still feel firm
  3. Stop as soon as it is safe and investigate Correct answer.
  4. Continue to the next exit and then check

Explanation

A low air pressure warning means the air brake system may not have enough pressure to stop the vehicle safely. Pull over as soon as it is safe and do not continue until the problem is corrected.

Question 21Driving Safely

Why should a CMV driver avoid using a retarder on a slippery road surface?

  1. It increases the stopping distance on dry roads
  2. It disables the anti-lock brake system
  3. It reduces fuel economy significantly
  4. It can cause the drive wheels to lose traction Correct answer.

Explanation

An engine or driveline retarder applies braking force at the drive wheels and can cause them to skid on wet, icy, or slippery pavement. Turn the retarder off when traction is poor.

Question 22Driving Safely

How does total stopping distance relate to perception and reaction time?

  1. It is only the distance traveled while braking
  2. It includes perception, reaction, and braking distance Correct answer.
  3. It is the same as the following distance
  4. It depends only on the vehicle's weight

Explanation

Total stopping distance is the sum of the distance traveled while perceiving a hazard, the distance during reaction time, and the actual braking distance. All three components increase with speed.

Question 23Driving Safely

A driver must descend a steep grade with a heavy load. Which technique best controls speed?

  1. Ride the brakes lightly the entire way
  2. Shift to neutral and use the brakes
  3. Apply the brakes hard at the bottom of the grade
  4. Select a low gear before the grade and use engine braking Correct answer.

Explanation

Select a low gear before starting down the grade and let engine braking control speed, using the brakes only as needed. This prevents brake fade and keeps the vehicle under control.

Question 24Driving Safely

You are driving a CMV and a front tire blows out. What is the safest immediate action?

  1. Brake hard and steer to the shoulder
  2. Accelerate to stabilize the vehicle
  3. Turn sharply away from the blowout
  4. Hold the wheel firmly and slow gradually Correct answer.

Explanation

With a front tire blowout, grip the wheel firmly, keep the vehicle straight, and slow gradually before pulling off the road. Hard braking or sharp steering can cause a loss of control or rollover.

Question 25Driving Safely

Under Oklahoma law, what is the maximum speed limit for a commercial motor vehicle on an interstate highway unless a lower limit is posted?

  1. 55 mph
  2. 65 mph
  3. 70 mph
  4. 75 mph Correct answer.

Explanation

Oklahoma sets the maximum posted limit on rural interstate highways at 75 mph, and this applies to commercial vehicles unless a sign shows a lower limit for trucks. Drivers must always obey the lower posted figure when one exists.

Question 26Driving Safely

You are driving a CMV and begin to feel a steady thumping vibration through the steering wheel that grows stronger as speed increases. What is the most likely cause and the safest response?

  1. Worn shock absorbers; maintain speed and check them at the next terminal
  2. A loose exhaust hanger; accelerate briefly to clear the vibration
  3. An unbalanced or damaged front tire; slow down gradually and stop to inspect Correct answer.
  4. Normal road surface feedback; no action is required

Explanation

A vibration that increases with speed usually points to an out-of-balance, misaligned, or damaged front tire or wheel, which can lead to a blowout. The safe response is to reduce speed smoothly, avoid hard braking, and stop in a safe place to inspect the tire and wheel.

Question 27Driving Safely

In Oklahoma, when are you required to dim your high-beam headlights for an oncoming vehicle?

  1. Within 1,000 feet of the oncoming vehicle Correct answer.
  2. Only after the other driver dims first
  3. Only when the other vehicle is a commercial truck
  4. Within 500 feet of the oncoming vehicle

Explanation

Oklahoma's driver manual directs drivers to dim high-beam headlights when an oncoming vehicle is within 1,000 feet. Switching to low beams reduces glare and helps the approaching driver see the road.

Question 28Driving Safely

You are driving a loaded CMV on a wet road and need to stop quickly. How should you apply the brakes if your vehicle has antilock brakes (ABS)?

  1. Apply steady, firm pressure and hold it while steering Correct answer.
  2. Apply light pressure and release if you feel any pedal pulsation
  3. Brake only with the trailer hand valve
  4. Pump the brake pedal rapidly to avoid locking the wheels

Explanation

With ABS you should press the brake pedal firmly and hold it; the system modulates pressure to prevent wheel lockup, so pumping defeats its purpose. You can steer while braking hard because ABS maintains some steering control.

Question 29Driving Safely

What does a flashing red traffic signal require a CMV driver to do?

  1. Treat it as a green light for right turns only
  2. Stop completely, then proceed when it is safe Correct answer.
  3. Yield only to vehicles already in the intersection
  4. Slow down and proceed with caution without stopping

Explanation

A flashing red signal operates like a stop sign: come to a complete stop, yield to traffic and pedestrians with the right of way, and proceed only when it is safe. Rolling through without a full stop violates the law.

Question 30Driving Safely

You must drive a CMV through a work zone where lanes are narrowed and workers are present. Which action best reduces risk?

  1. Speed up to clear the zone before traffic backs up
  2. Maintain the posted work-zone speed and increase your following distance Correct answer.
  3. Follow the vehicle ahead closely so no one cuts in
  4. Turn on your high beams to warn workers

Explanation

Work zones combine narrow lanes, workers near the roadway, and sudden speed changes, so obeying the reduced posted limit and leaving extra following room gives you time to react. Fines are typically doubled for violations in work zones.

Question 31Driving Safely

When driving a CMV, why should you check your mirrors before slowing for a stop?

  1. To verify your lane position relative to the shoulder
  2. To see whether traffic behind you is closing too fast Correct answer.
  3. To confirm your trailer lights are working
  4. To decide whether to use the engine brake

Explanation

A heavy CMV takes far longer to stop than a car, so a driver behind may not expect your slower deceleration. Checking mirrors before braking lets you judge closing traffic and adjust your stop to avoid being rear-ended.

Question 32Driving Safely

A CMV driver is convicted of a serious traffic violation. What is the effect on the driver's commercial driving privilege under federal and state rules?

  1. Disqualification occurs only after five serious violations
  2. Two serious violations within three years result in disqualification Correct answer.
  3. Only violations in Oklahoma count toward disqualification
  4. A single serious violation has no effect unless it involves alcohol

Explanation

Under CDL rules adopted by Oklahoma, two serious traffic violations committed within a three-year period disqualify a driver for at least 60 days. Serious violations include excessive speeding, reckless driving, and improper lane changes.

Question 33Driving Safely

You are driving a CMV through a long tunnel with artificial lighting. What is the correct lighting practice?

  1. Turn on your low-beam headlights Correct answer.
  2. Rely on the tunnel lighting and leave headlights off
  3. Turn on high beams to see farther
  4. Use only parking lights

Explanation

Low beams make your vehicle visible to others and help you see in the transition zones at the tunnel entrance, where lighting changes sharply. High beams reflect off the walls and can blind other drivers.

Question 34Driving Safely

What is the proper way to use a fire extinguisher on a small vehicle fire?

  1. Aim at the top of the flames and sweep downward
  2. Aim at the base of the fire and sweep side to side Correct answer.
  3. Spray from as far away as possible to stay safe
  4. Open the hood fully before spraying into the engine

Explanation

Aim at the base of the flames, where the fuel is burning, and sweep side to side until the fire is out. Fully opening the hood feeds oxygen to an engine fire and can cause it to flare up.

Question 35Driving Safely

When must a CMV driver place warning devices such as reflective triangles after a breakdown on a divided highway?

  1. Within 10 minutes of stopping, placed as required by the location Correct answer.
  2. Only at night or in bad weather
  3. Only if the vehicle blocks a travel lane
  4. Only if the vehicle is carrying hazardous materials

Explanation

After stopping on a highway, warning devices must be placed within 10 minutes to alert approaching traffic. Placement distances vary with the road type: 10 feet from the vehicle, 100 feet behind, and additional devices as required.

Question 36Driving Safely

You are about to cross a bridge that has a posted weight limit lower than your loaded vehicle's weight. What should you do?

  1. Take an alternate route that avoids the bridge Correct answer.
  2. Cross slowly to reduce the load on the structure
  3. Cross in a lower gear to spread the weight
  4. Stop on the bridge and check the deck first

Explanation

A posted weight limit means the structure cannot safely carry more than that load, and slowing down does not reduce the weight. The driver must find another route or reduce the load before crossing.

Question 37Driving Safely

How should a CMV driver respond when an emergency vehicle approaches with siren and flashing lights?

  1. Move to the left lane and continue at the same speed
  2. Pull to the right edge of the roadway and stop until it passes Correct answer.
  3. Stop immediately wherever you are
  4. Speed up to stay ahead of the emergency vehicle

Explanation

Yield by pulling to the right edge of the road and stopping until the emergency vehicle passes, keeping intersections clear. Stopping abruptly in a travel lane can block the emergency vehicle and cause a collision.

Question 38Driving Safely

What is 'hydroplaning' and what should a CMV driver do if it occurs?

  1. The tires grip better on wet pavement; maintain speed
  2. The brakes overheat from water; apply them firmly to dry them
  3. The tires ride on a film of water; ease off the accelerator and avoid hard braking Correct answer.
  4. The steering locks in a turn; turn the wheel harder

Explanation

Hydroplaning happens when water lifts the tires off the pavement so they lose contact, eliminating traction and steering. Ease off the accelerator, keep the wheel steady, and avoid hard braking until the tires regain contact.

Question 39Driving Safely

You are driving a CMV and the traffic light ahead turns yellow as you approach. What is the safest decision?

  1. Continue at the same speed and honk
  2. Stop if you can do so safely before the intersection Correct answer.
  3. Accelerate to clear the intersection before it turns red
  4. Swerve into the adjacent lane to keep moving

Explanation

A yellow signal warns that the light is about to turn red; stop if you can do so safely. A heavy vehicle cannot stop quickly, so the decision must be made early, and accelerating or swerving to beat the light risks a collision.

Question 40Driving Safely

What should a CMV driver do when driving in strong crosswinds on an open highway?

  1. Open the driver's window to equalize pressure
  2. Increase speed to push through the wind
  3. Move to the left lane to avoid the wind
  4. Reduce speed and keep a firm grip with both hands on the wheel Correct answer.

Explanation

Crosswinds can push a high-profile CMV out of its lane, especially when leaving a sheltered area like a bridge or building. Slowing down and holding the wheel firmly with both hands helps you correct smoothly without oversteering.

Question 41Driving Safely

You are driving a CMV and the rear wheels of your vehicle begin to skid on a wet road. What should you do?

  1. Brake hard and hold the wheel straight
  2. Accelerate to pull the vehicle straight
  3. Turn the wheel sharply opposite the skid
  4. Release the brake and steer in the direction you want the rear to go Correct answer.

Explanation

When the rear wheels skid, release the brake and steer in the direction you want the rear of the vehicle to travel so the wheels realign with the direction of motion. Hard braking or sharp counter-steering can turn the skid into a spin.

Question 42Driving Safely

What is the correct way to check that your trailer brakes are operating before a trip?

  1. Apply the trailer hand valve while moving at highway speed
  2. Rely on the ABS warning lamp only
  3. Press the brake pedal while parked and listen for leaks
  4. Pull the tractor protection valve and test the brakes at low speed Correct answer.

Explanation

A proper check involves building air pressure, releasing the parking brake, and applying the trailer brakes with the hand valve or tractor protection valve at low speed to confirm they hold. The test should be done at walking speed in a safe area.

Question 43Driving Safely

Why should a CMV driver avoid coasting with the transmission in neutral or with the clutch disengaged?

  1. It causes the ABS to disengage
  2. It wears the clutch faster
  3. It increases fuel consumption noticeably
  4. It reduces control because engine braking is lost and is illegal in many states Correct answer.

Explanation

Coasting in neutral removes engine braking and reduces your ability to control speed, especially on downgrades, and it is prohibited in many jurisdictions. Keeping the transmission engaged preserves braking and control.

Question 44Driving Safely

You are hauling a load that shifts during a turn. What is the best immediate action?

  1. Accelerate through the curve to finish the turn quickly
  2. Continue at the same speed to stabilize the load
  3. Brake hard to stop the shift
  4. Slow down gradually and stop in a safe place to check the load Correct answer.

Explanation

A shifting load can change the vehicle's center of gravity and may become unstable or fall off, so reduce speed smoothly and stop in a safe area to inspect and secure it. Hard braking or accelerating can worsen the shift.

Question 45Driving Safely

What is the purpose of the 'S' in the SIPDE defensive driving process used by commercial drivers?

  1. Slow the vehicle before every intersection
  2. Signal your intentions to other drivers
  3. Search the roadway ahead for hazards Correct answer.
  4. Steer around obstacles without braking

Explanation

SIPDE stands for Search, Identify, Predict, Decide, and Execute; the search step means scanning the roadway well ahead for hazards. Early scanning gives a heavy vehicle the time and distance it needs to respond.

Question 46Driving Safely

When driving a CMV at night, what is the main reason to reduce your speed below the posted limit?

  1. Other drivers are less likely to use turn signals
  2. Your headlights do not let you see as far as you can stop Correct answer.
  3. Night air pressure reduces tire grip
  4. Engine temperature runs higher at night

Explanation

At night your visibility is limited to the reach of your headlights, so you must be able to stop within that distance. If you cannot, you are overdriving your lights and should slow down.

Question 47Driving Safely

You are driving a CMV and a tire blows out on a drive axle. Which action is most appropriate?

  1. Pull the parking brake to stop quickly
  2. Brake hard and steer for the shoulder immediately
  3. Release the wheel and let the vehicle slow on its own
  4. Hold the wheel firmly, ease off the accelerator, and slow gradually Correct answer.

Explanation

A blowout can pull the vehicle to one side, so grip the wheel firmly, ease off the accelerator, and let the vehicle slow gradually before moving off the road. Hard braking or the parking brake can cause a loss of control or a spin.

Question 48Driving Safely

What does a yellow diamond-shaped warning sign with a downward arrow and a percentage indicate to a CMV driver?

  1. A steep downgrade ahead requiring a lower gear Correct answer.
  2. A soft shoulder ahead
  3. A reduced weight limit ahead
  4. A lane merge ahead

Explanation

A downward arrow with a percentage on a yellow diamond warns of a steep grade ahead and shows its steepness. Drivers should select a safe gear before the grade and control speed without overusing the brakes.

Question 49Driving Safely

You are driving a CMV with a hazardous materials load and must stop at a railroad crossing. Which practice is correct?

  1. Cross only when another truck goes first
  2. Stop, look and listen, and cross only when the tracks are clear Correct answer.
  3. Cross without stopping if the gate is up
  4. Stop on the tracks to check for trains in both directions

Explanation

Vehicles carrying hazardous materials must stop at railroad crossings, look and listen, and proceed only when the tracks are clear. Stopping on the tracks is always dangerous and prohibited.

Question 50Driving Safely

Under Oklahoma and federal CDL rules, what is the minimum following distance a CMV driver should keep behind the vehicle ahead under ideal conditions?

  1. A fixed distance of 50 feet at any speed
  2. Two car lengths at speeds under 30 mph
  3. One second for every ten feet of vehicle length, with a minimum of one second below 40 mph Correct answer.
  4. One second per 10 mph of speed, regardless of vehicle length

Explanation

The standard rule for commercial vehicles is one second of following distance for each ten feet of vehicle length. When traveling under 40 mph, a minimum of one second is used because the calculation would otherwise produce an unrealistically short gap. At highway speed a 60-foot combination vehicle therefore needs at least six seconds.