Gross Combination Weight Rating

TX · GK Endorsement

Texas General Knowledge CDL Practice Test

Below are 25 exam-style questions for the Texas General Knowledge CDL knowledge test, modeled on the FMCSA-aligned content used by the Texas Department of Public Safety. Try to answer each question on your own before reading the answer key directly under it. The questions and answer choices are shuffled deterministically per state and endorsement, so the order will stay the same on repeat visits — that lets you genuinely measure your improvement.

Heads up: this is a study tool, not a graded exam. Cover the answer with your hand or a sheet of paper for an honest practice run, then re-read the explanations for any questions you missed. Aim for 22 out of 25 or better, three times in a row, before scheduling the real exam.

Question 1 of 25

Engine retarders (Jake brakes) should be turned off when:

A Driving in dry conditions
B On any downgrade
C Roads are wet, icy, or snow-covered
D In residential areas only because of noise

Correct answer: C

Retarders can cause drive-wheel skids on slippery surfaces. Turn them off when traction is reduced.

Question 2 of 25

A Class C CDL is required to drive:

A Any vehicle over 26,001 lbs
B Class A combinations only
C Vehicles designed to carry 16+ passengers including the driver, or that require hazmat placards
D Tractor-trailers under 26,001 lbs GCWR

Correct answer: C

Class C covers vehicles that don't meet Class A or B but are designed to carry 16 or more passengers (including the driver) or carry placarded amounts of hazardous materials.

Question 3 of 25

A driver should secure cargo so it:

A Fills the trailer floor edge to edge
B Looks neat from the outside
C Is loaded in the order it will be delivered
D Cannot shift on stops, starts, or turns and is within axle weight limits

Correct answer: D

The legal standard is securement against forces during normal driving conditions plus an emergency stop, and within axle and total weight limits.

Question 4 of 25

You may not drive a CMV with a blood-alcohol concentration of:

A 0.08% or higher
B 0.10% or higher
C 0.04% or higher
D Any detectable amount above 0.00%

Correct answer: C

0.04% is the regulatory limit for CMV operation. A detectable amount under that triggers an out-of-service order but is not necessarily a DUI conviction.

Question 5 of 25

Which of the following is a sign of fatigue?

A All of the above
B Trouble remembering the last few miles
C Drifting in your lane
D Frequent yawning

Correct answer: A

All three are classic fatigue indicators in the FMCSA model. Cold air, music, and caffeine are not effective fixes — only sleep is.

Question 6 of 25

Which is true about driving in mountains?

A Engine braking helps keep speed under control
B Brakes alone are not designed to hold a heavy vehicle on a long downgrade
C All of the above
D Heavy vehicles can slow down sharply on grades

Correct answer: C

Mountain driving combines all three. Use of low gears, engine braking, and short, moderate service-brake applications is the safe combination.

Question 7 of 25

The proper response to a tire blowout on the front axle is to:

A Hold the steering wheel firmly, ease off the accelerator, and let the vehicle slow down
B Shift to neutral and coast
C Steer sharply toward the shoulder
D Brake immediately and pull off the road

Correct answer: A

Hard braking after a blowout can cause loss of control. Hold the wheel, release the accelerator, and let speed bleed off before braking gently.

Question 8 of 25

Black ice is most likely on:

A Bridges and overpasses
B Concrete pavement only
C Gravel surfaces
D Roads in direct sunlight

Correct answer: A

Bridges and overpasses freeze first because cold air circulates above and below them. They are the most-asked test scenario for sudden ice.

Question 9 of 25

What does GVWR stand for?

A Gross Vehicle Weight Rating
B General Vehicle Weight Reading
C Government Vehicle Weight Regulation
D Gross Vehicle Width Rating

Correct answer: A

GVWR is the maximum weight the manufacturer says a single vehicle can safely weigh, including itself plus its load.

Question 10 of 25

Which is required when stopping on the side of a level, straight, two-lane road?

A Three reflective triangles: 10 ft, 100 ft, and 200 ft toward approaching traffic
B One reflective triangle within 10 feet
C A spotter walking 1,000 ft up the road
D A flare burning constantly

Correct answer: A

On a level straight road, place triangles 10 feet behind the vehicle, 100 feet, and 200 feet to the rear in the direction of approaching traffic.

Question 11 of 25

A driver's blood-alcohol concentration (BAC) of 0.04% or higher while operating a commercial motor vehicle is:

A Allowed off-duty only
B Allowed if the driver feels fine
C Considered driving under the influence for CDL purposes
D A traffic violation, but not a CDL disqualification

Correct answer: C

Federal rules treat 0.04% BAC in a CMV as DUI for CDL purposes — half the typical 0.08% limit for non-commercial drivers.

Question 12 of 25

When should you use four-way flashers?

A Only at night
B When you are stopped or moving slowly enough to be a hazard
C Whenever you feel like it
D Only on the highway

Correct answer: B

Four-ways are for vehicles stopped on or near the road or moving so slowly that they are a hazard.

Question 13 of 25

On a long downgrade, why is it dangerous to use the brakes too much?

A It triggers the ABS warning light
B It wastes brake pads
C It cools the brakes too much
D Brake fade can leave you with reduced or no braking power

Correct answer: D

Heat from continuous braking causes the friction surfaces to lose their grip. Use a low gear and brief, moderate brake applications.

Question 14 of 25

When you double your speed, your stopping distance approximately:

A Triples
B Stays the same
C Quadruples
D Doubles

Correct answer: C

Braking distance increases roughly with the square of speed; doubling speed quadruples the braking distance. Reaction distance only doubles, but the total grows quickly.

Question 15 of 25

Acceleration must be smooth and gradual to avoid:

A Powertrain wear and possible loss of control on slippery surfaces
B Wasting fuel only
C Annoying passengers
D Engine damage

Correct answer: A

Quick throttle inputs on slick surfaces can spin the drive wheels and cause a tractor jackknife. Smooth acceleration avoids this and reduces wear.

Question 16 of 25

When driving at night, you should adjust speed so that you can stop within:

A The range of your low-beam headlights
B Half the range of your low-beam headlights
C The full range of high-beam headlights when in use
D Whatever speed feels safe

Correct answer: A

Always be able to stop within the distance you can see. At night with low beams, that's typically about 250 feet.

Question 17 of 25

Stopping distance is made up of:

A Speed times weight
B Perception distance + reaction distance + brake-lag distance + braking distance
C Reaction distance only
D Brake-lag distance only

Correct answer: B

Total stopping distance has four parts. Air brakes add a brake-lag distance not present in hydraulic systems.

Question 18 of 25

The maximum allowable on-duty driving time after 8 consecutive hours off duty is:

A 16 hours
B 14 hours
C 10 hours
D 11 hours

Correct answer: D

After 10 hours off duty, a property-carrying driver may drive up to 11 hours, within a 14-hour on-duty window.

Question 19 of 25

When approaching a steep downgrade, the basic safe-driving rule is:

A Use the parking brake intermittently
B Coast in neutral
C Select a lower gear before starting down
D Stay in high gear

Correct answer: C

Get into a low gear before the descent so the engine helps hold the vehicle back.

Question 20 of 25

Stab braking is used:

A On vehicles with ABS
B On vehicles without ABS, to keep them straight in an emergency
C To save fuel
D On wet roads only

Correct answer: B

Stab braking — full application then release as soon as wheels lock, then re-apply — is for non-ABS vehicles. With ABS, do not pump.

Question 21 of 25

GCWR stands for:

A Gross Combination Weight Rating
B General Carrier Weight Rating
C Gross Cargo Weight Rating
D Government Combination Weight Reading

Correct answer: A

GCWR is the maximum allowable weight of a power unit plus a towed unit, including all cargo. It determines whether a license is Class A.

Question 22 of 25

When checking the engine compartment, you should make sure that:

A Coolant level is above LOW and the cap is secure
B Engine oil level is safe to operate
C Power steering fluid is at the proper level
D All of the above

Correct answer: D

A proper engine-compartment check covers oil, coolant, power steering fluid, windshield washer fluid, hoses, belts, and electrical wiring. Skipping any one of them defeats the purpose of the inspection.

Question 23 of 25

Which is true about the use of turn signals?

A Signal only when other vehicles are present
B Use the four-way flashers instead of signals at intersections
C Signal only at the moment you start turning
D Signal early, signal continuously, and cancel after the turn

Correct answer: D

The federal model manual specifies signal early, continuously, and cancel after — the same three steps every state CDL test asks about.

Question 24 of 25

You are driving a heavy vehicle and have to stop on a long downgrade. Which is the safest way?

A Use the parking brake to slow down
B Use a low gear and steady moderate brake application
C Disengage the clutch and coast
D Pump the brakes hard and fast

Correct answer: B

On a long downgrade, select a low gear before the descent and use steady, light to moderate braking. Hard pumping or coasting in neutral leads to brake fade and loss of control.

Question 25 of 25

What is the most important reason for doing a vehicle inspection?

A Safety for yourself and other road users
B To meet your dispatcher's schedule
C To reduce tire wear
D To improve fuel economy

Correct answer: A

Federal rules and the FMCSA model manual list safety as the single most important reason for a pre-trip inspection. Mechanical defects discovered before the trip cannot kill anyone on the highway.

Study tips for the Texas General Knowledge exam

The General Knowledge portion of the Texas CDL exam is graded out of the bank of questions the Texas Department of Public Safety draws from each year. While the exact bank is not published, every question is sourced from the General Knowledge chapter of the Texas CDL handbook, which itself is derived from the FMCSA Model Commercial Driver's License Manual. That means studying our practice tests, reading the corresponding handbook chapter, and re-reading the parts you got wrong is genuinely the most efficient route to a first-time pass.

Most successful applicants follow a simple cycle: take the practice test cold, write down every question you missed, open the matching chapter of the official Texas handbook, re-read the section that contains the right answer, then re-take the practice test 24 to 48 hours later. The 24-hour delay matters — sleep is when your brain commits new information to long-term memory, and CDL knowledge questions reward that kind of consolidated learning rather than cramming.

Pay particular attention to questions that include qualifier words like always, never, only, primary, or most. CDL test writers love to flip the right answer with a single qualifier. When two answer choices look almost identical, pay attention to the verb (is it must, should, or may?) and to any numbers (14 days, 100 air miles, 8 hours, 70/8 split). On endorsement tests in particular, watch for trick framing where a true statement about a different endorsement is offered as the "correct" answer to a question that is actually about General Knowledge.

Test-day logistics matter too. Bring photo ID, your Social Security card or birth certificate, your medical examiner's certificate (DOT card), and proof of state residency if you haven't already submitted those documents. The Texas Department of Public Safety will not let you sit for the knowledge exam without your documentation, and most offices charge an additional fee for re-attempts. Arrive early — the wait at most CDL testing offices runs 30 to 60 minutes — and silence your phone before the exam begins.

Finally, keep your General Knowledge fundamentals sharp even when you're focused on the General Knowledge exam. Many states administer multiple knowledge tests in a single sitting, and questions on weight definitions (GVWR, GCWR, GAWR), stopping distance, and the pre-trip inspection routine show up across endorsements. If you're unsure on the basics, sit a fresh Texas General Knowledge practice test before scheduling the real exam.

Next steps

Missed more than four questions? Re-read the General Knowledge study guide and the matching chapter in the official Texas CDL handbook. Then come back and re-take the test. Once you can score 22 of 25 or higher on three runs in a row, you're in good shape to schedule the real exam at your local Texas Department of Public Safety office.

Already comfortable with this endorsement? Drill another: TX Air Brakes · TX Combination Vehicles · TX Hazardous Materials · TX Passenger · TX School Bus · TX Tank Vehicle · TX Doubles / Triples

New to the CDL process in Texas? Read How to apply for a CDL in Texas for the document checklist and step-by-step timeline.