Florida General Knowledge CDL Practice Test

This is a free 20-question practice test for the General Knowledge portion of the Florida Commercial Driver's License knowledge exam. Questions are pulled from a pool of 97 drawn from the AAMVA CDL Manual, which is the source document the Florida Department of Highway Safety and Motor Vehicles uses to write its actual exam.

How it works: Click an answer. The correct choice highlights in green, and you'll see a short explanation. Aim for 85% or better before you sit for the real test in Florida.

Question 1 of 20

You are driving a 40-foot vehicle at 35 mph. The minimum following distance you should maintain is:

2 seconds
3 seconds
4 seconds
7 seconds

Correct. The rule of thumb: 1 second per 10 feet of vehicle length below 40 mph. A 40-foot vehicle therefore needs 4 seconds of following distance.

Question 2 of 20

Most drivers who fall asleep at the wheel:

Are aware they are tired and pull over
Do not realize they are about to fall asleep
Have been drinking
Have been on the road less than an hour

Correct. Most drivers who fall asleep do not realize how drowsy they are. The only fix is to stop and rest before fatigue reaches that point.

Question 3 of 20

A driver who has been disqualified is:

Allowed to drive a commercial vehicle
Not allowed to drive a commercial vehicle
Allowed to drive only with another driver in the cab
Allowed to drive only on private property

Correct. A disqualified driver may not operate a commercial motor vehicle on public roads, regardless of supervision.

Question 4 of 20

What is the only effective way to remove alcohol from the body?

Drinking coffee
Cold showers
Eating a heavy meal
Time

Correct. Only time eliminates alcohol from the body — at roughly one drink per hour. Coffee, food, and showers do not speed up the process.

Question 5 of 20

When you exit a highway in a heavy commercial vehicle, you should:

Maintain highway speed onto the ramp
Slow down before reaching the ramp curve, since posted advisory speeds assume cars
Speed up to clear the ramp
Brake only at the bottom

Correct. Posted ramp speeds assume passenger cars. A loaded heavy vehicle, especially with high CG, can roll over at the posted speed. Slow before the curve.

Question 6 of 20

On a tight curve in a rural mountain road:

Approach at posted speed
Slow down before entering the curve, take a wider line if you can do so safely
Speed up
Stay on the centerline

Correct. Mountain curves often have advisory speeds well below your safe load speed. Slow before entering and use the full lane safely.

Question 7 of 20

Which of these is the best advice for staying alert on a long trip?

Drink coffee
Take cold pills
Get enough sleep before the trip and take rest breaks
Open the window

Correct. Adequate sleep before driving and scheduled rest breaks are the only reliable strategies. Coffee and cold air mask fatigue but do not eliminate it.

Question 8 of 20

A "convex mirror" on the side of a tractor:

Provides a wider view, but objects appear smaller and farther away than they really are
Magnifies objects
Has a flat reflection
Cannot be used in daylight

Correct. Convex (curved) mirrors widen the field of view but distort distance perception — objects look smaller and farther than they actually are.

Question 9 of 20

A tire may need replacement if:

Tread depth is below the minimum (4/32 steer, 2/32 other), there are sidewall cuts, exposed cord, or other damage
It looks dirty
It is over a year old
It is the wrong color

Correct. Below-minimum tread depth, sidewall damage, exposed cords, bulges, or excessive wear are all reasons to replace.

Question 10 of 20

The "implied consent" rule means:

You agree to chemical testing for alcohol and drugs by holding a CDL and operating a commercial vehicle
Police need a warrant for any test
You may refuse all tests with no penalty
It applies only to passenger cars

Correct. By holding a CDL and operating a CMV on public roads, you have given implied consent to alcohol and drug testing. Refusing testing leads to disqualification just as a positive test does.

Question 11 of 20

Which of the following can cause the wheels of your vehicle to skid on a curve?

Driving below the posted speed limit
Driving too fast for the curve
Slowing down before entering the curve
Driving with a light load

Correct. Posted curve advisory speeds assume cars; a heavy commercial vehicle with a high center of gravity may roll over or skid even at the posted speed. Slow before the curve, accelerate gently through it.

Question 12 of 20

The blood-alcohol concentration (BAC) at or above which a CDL driver is considered to be driving under the influence in a commercial motor vehicle is:

Correct. The federal BAC limit for CDL drivers operating a commercial vehicle is .04 — half the .08 limit for non-commercial drivers in most states.

Question 13 of 20

Which of these is true about following distance for heavy vehicles?

It can be the same as a passenger car
It must be longer because heavy vehicles take longer to stop
It is irrelevant in city driving
It only matters at night

Correct. Greater weight = longer stopping distance. Use one second per 10 feet of vehicle length below 40 mph, plus an extra second above 40.

Question 14 of 20

A driver-side skid can cause a tractor-trailer to:

Drift gently
Jackknife
Improve steering
Over-correct only the trailer

Correct. When the drive wheels lose traction and the trailer continues forward, the tractor pivots and the rig jackknifes.

Question 15 of 20

What is the minimum tread depth required for the front (steering) tires of a commercial vehicle?

1/32 inch
2/32 inch
4/32 inch
6/32 inch

Correct. Steer-axle tires must have at least 4/32-inch tread depth in every major groove. Other tires require at least 2/32 inch.

Question 16 of 20

The four-way flashers on a commercial vehicle should be used:

Anytime you are stopped or moving slowly enough that other drivers might not expect
Only when parked
Only at night
Only on the interstate

Correct. Use four-way flashers anytime your vehicle is stopped on or near the roadway, or moving slowly enough that approaching traffic might be surprised.

Question 17 of 20

Which is the proper position for your hands on the steering wheel?

Both hands on the same side
One hand on top, one in your lap
Both hands firmly on opposite sides of the wheel (e.g., 9 and 3)
One hand on the wheel, one on the gear shift

Correct. Both hands should be on opposite sides of the wheel — typically the 9 o'clock and 3 o'clock positions — for steering control.

Question 18 of 20

You are driving on a two-lane road. An oncoming driver drifts into your lane. You should:

Steer right onto the shoulder
Flash your high beams
Honk your horn
Brake hard and stop in your lane

Correct. When an oncoming driver drifts into your lane, the safer escape is right onto the shoulder. Steering left risks a head-on if the other driver corrects.

Question 19 of 20

When a vehicle ahead of you brakes hard, you should:

Brake harder
Apply the brakes immediately, even if you don't need to
Look for a way to steer around the vehicle if necessary, while preparing to brake
Honk to warn the driver behind you

Correct. Plan your escape: identify a clear lane or shoulder. If you can steer to safety, you save reaction time. If not, brake firmly without locking the wheels.

Question 20 of 20

When driving down a long, steep downgrade, you should:

Hold the brakes lightly the whole way down
Select the proper gear before starting down and use intermittent firm brake applications
Coast in neutral
Use only the engine brake

Correct. Select a low gear before starting down. Use the brakes in firm, intermittent applications: brake until 5 mph below safe speed, release until safe speed is regained, repeat. Continuous brake application overheats the brakes.

About the Florida General Knowledge exam

Most state DMVs administer 50 General Knowledge questions and require 80% (40 correct) to pass. Questions are pulled from a much larger pool, so two applicants taking the test on the same day will see different mixes. The questions on this site are drawn from the AAMVA CDL Manual chapters that every state's exam is built from.

The Florida Department of Highway Safety and Motor Vehicles follows the federal CDL standards established by FMCSA. To earn the General Knowledge credential, you must answer at least 80% of the questions correctly. Many candidates score lower the first time because the test pulls from a large pool — refreshing this page will give you a different mix of questions, drawn from the same authoritative source.

Want more practice? Try the full General Knowledge question bank or browse all Florida CDL practice tests.