Indiana General Knowledge CDL Practice Test

This is a free 20-question practice test for the General Knowledge portion of the Indiana 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 Indiana Bureau of 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 Indiana.

Question 1 of 20

Empty trucks:

Always stop in less distance than fully loaded ones
Require longer stopping distances than loaded ones because of lighter brake force per axle
Have the same stopping distance as loaded trucks
Cannot use the engine brake

Correct. An empty truck has lighter axle weight, so the brakes generate less friction relative to vehicle weight — the truck can take longer to stop than the same vehicle loaded.

Question 2 of 20

You should never drive your vehicle if the brake-system warning device:

Comes on
Goes out
Flickers
Comes on briefly at startup

Correct. A continuously lit or sounding low-air warning means dangerous brake-system pressure loss. Stop safely and have the system serviced.

Question 3 of 20

When approaching a curve, you should:

Brake during the curve
Slow down before the curve, then accelerate gently through it
Maintain steady speed
Speed up to maintain control

Correct. Slow before entering the curve. Once in the curve, accelerate gently to maintain stability — braking in a curve invites a skid or rollover.

Question 4 of 20

If your vehicle hydroplanes, what should you do?

Brake hard immediately
Steer sharply to recover
Release the accelerator and push in the clutch
Accelerate to push through

Correct. Release the accelerator and push in the clutch. Do not brake or steer hard until the tires regain contact.

Question 5 of 20

Which of the following is the best way to prevent a fire in your vehicle?

Carry extra fuel
Smoke only with the windows open
Inspect the vehicle, watch the gauges, and use safe driving practices
Run the engine hot to burn off carbon

Correct. Most fires are preventable through inspection (electrical, fuel-system, tire) and watching gauges, plus prohibiting smoking near fuel and observing safe loading/refueling rules.

Question 6 of 20

What is the minimum amount of tread depth required on tires other than front (steering) tires?

1/32 inch
2/32 inch
4/32 inch
5/32 inch

Correct. Non-steer tires must have at least 2/32-inch tread depth in every major groove.

Question 7 of 20

Which of these is a sign of tire failure?

Heavy thumping or vibration
A loud bang
The vehicle pulling to one side
All of the above

Correct. Vibration, a loud bang from a blowout, and pulling to one side are all classic signs of tire failure.

Question 8 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 9 of 20

Which lane is generally the best for a commercial vehicle on a multi-lane highway?

The far left (passing) lane
The middle lane
The right lane (slow lane)
Whichever has the lightest traffic

Correct. The right lane is generally best — it limits lane changes, reduces conflict with merging traffic only on the right, and matches commercial-vehicle speed.

Question 10 of 20

You are driving a 60-foot tractor-trailer at 55 mph. The minimum following distance you should maintain is:

4 seconds
5 seconds
6 seconds
7 seconds

Correct. Above 40 mph, add one extra second to the per-10-foot rule. A 60-foot vehicle = 6 seconds + 1 = 7 seconds at 55 mph.

Question 11 of 20

A fully loaded tractor-trailer traveling at 55 mph on dry pavement requires roughly what total stopping distance (perception + reaction + braking)?

100 feet
200 feet
300 feet (about the length of a football field)
600 feet

Correct. Total stopping distance for a heavy commercial vehicle at 55 mph on dry pavement is approximately 300 feet, or the length of a football field including end zones.

Question 12 of 20

When approaching a railroad crossing, drivers of buses, school buses, and placarded hazmat vehicles must:

Speed up to clear quickly
Stop between 15 and 50 feet from the nearest rail and listen
Cross only if a train is in sight
Sound the horn

Correct. Buses, school buses, and placarded hazmat vehicles must stop at every crossing, 15 to 50 feet from the nearest rail. Look and listen, then proceed when safe.

Question 13 of 20

Which type of fire extinguisher should you use on an electrical fire?

Class A
Class B
Class C
Class D

Correct. Class B:C dry-chemical extinguishers (often labeled "B:C" or "ABC") are appropriate for electrical fires. Never use water on an electrical fire.

Question 14 of 20

You are driving on a steep downgrade and your brakes have failed. The best escape is to:

Pump the brakes furiously
Use a runaway escape ramp
Try to bail out of the cab
Sound the horn and continue

Correct. If a runaway escape ramp is available, use it. Modern arrester beds use loose gravel or sand to slow the vehicle without injury to the driver.

Question 15 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 16 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 17 of 20

Wet brakes can cause:

Reduced braking power, brakes pulling to one side, or wheel lockup
Better braking
No effect on the brakes
Improved fuel economy

Correct. After driving through deep water, brakes may be wet — they can lose effectiveness, pull to one side, or grab. Apply the brakes lightly while driving slowly to dry them.

Question 18 of 20

What is "black ice"?

Ice that has been salted
A thin layer of ice clear enough that you can see the road through it
Ice on a black-painted road
Ice formed under the truck

Correct. Black ice is a thin, clear sheet of ice that looks like wet pavement. Suspect it whenever the temperature is at or below freezing and the road appears wet.

Question 19 of 20

Maximum allowable steering-wheel play is approximately:

5 degrees
10 degrees
20 degrees
30 degrees

Correct. Steering wheel play should not exceed 10 degrees (roughly 2 inches on a 20-inch wheel). More than that, the vehicle is hard to steer.

Question 20 of 20

Hazardous materials awareness is required for:

Only Hazmat-endorsed drivers
Every CDL holder, even without an H endorsement
Only owners
Only mechanics

Correct. Every CDL applicant must understand basic hazmat awareness — recognizing placards, labels, and shipping papers — even if they never haul hazmat.

About the Indiana 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 Indiana Bureau of 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 Indiana CDL practice tests.