Texas CDL General Knowledge Exam
Questions & Answers | A+ Graded Study
Guide for Commercial Driver’s License
Success
TEXAS CDL GENERAL KNOWLEDGE EXAM QUESTIONS & ANSWERS | A+ GRADED
STUDY GUIDE FOR COMMERCIAL DRIVER'S LICENSE SUCCESS
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• This comprehensive study guide contains carefully vetted multiple-choice
questions designed to prepare you for the Texas CDL General Knowledge Exam
with detailed EXPERT RATIONALE for each answer.
• Study systematically by reviewing each question, attempting the answer before
checking the correct response, and focusing on understanding the EXPERT
RATIONALE to master all CDL knowledge areas.
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1. What is the primary purpose of a pre-trip vehicle inspection?
A) To identify mechanical defects that could cause a crash or breakdown
B) To wash the outside of the vehicle
C) To check the driver's logbook
D) To monitor fuel consumption patterns
E) To test the emergency warning system
✓ Correct Answer: A - To identify mechanical defects that could cause a crash
or breakdown
EXPERT RATIONALE: A pre-trip inspection is a safety-critical procedure required by
federal law. Its primary purpose is to identify any mechanical problems, defects, or
unsafe conditions with the vehicle before operation. Finding issues like brake
problems, tire damage, or lighting failures before driving can prevent accidents and
breakdowns. While other tasks may be part of vehicle maintenance, only option A
directly addresses the primary safety purpose of the inspection.
,━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
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2. When performing a pre-trip inspection, which component should you check
first?
A) The cargo area
B) The engine compartment
C) The tires and wheels
D) The lighting system
E) The mirrors and windows
✓ Correct Answer: B - The engine compartment
EXPERT RATIONALE: The engine compartment should be checked first during a
pre-trip inspection. This allows you to assess critical fluid levels, belt condition,
hoses, and overall engine health before starting the vehicle. Checking the engine
compartment at the beginning ensures you can identify serious problems early that
might prevent safe operation. A systematic approach starting with the engine helps
organize the inspection efficiently and safely.
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━
3. What is the minimum tread depth required for the steering axle tires of a
commercial vehicle?
A) 2/32 of an inch
B) 4/32 of an inch
C) 6/32 of an inch
D) 8/32 of an inch
E) 10/32 of an inch
,✓ Correct Answer: B - 4/32 of an inch
EXPERT RATIONALE: Federal Motor Carrier Safety Regulations (FMCSR) require a
minimum tread depth of 4/32 of an inch on the steering axle tires and 2/32 of an
inch on all other tires. Steering axle tires require greater tread depth because they
are critical for vehicle control and direction. Insufficient tread depth can cause loss
of traction, hydroplaning, and reduced steering control, especially in wet conditions.
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━
4. Which of the following is NOT a proper way to check your tires during a pre-
trip inspection?
A) Look for bulges or blisters
B) Check for uneven wear patterns
C) Feel the tire with your hand to estimate pressure
D) Look for cuts or damage
E) Check that all valve stems are present
✓ Correct Answer: C - Feel the tire with your hand to estimate pressure
EXPERT RATIONALE: Feeling a tire with your hand cannot accurately determine tire
pressure. Tire pressure must be checked using a proper tire pressure gauge. A tire
can feel firm while being underinflated, or it may feel soft when properly inflated. A
pressure gauge is the only reliable method to verify correct tire pressure. All other
options are valid visual inspection methods for checking tire condition.
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
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5. How should you check the brake fluid level in a commercial vehicle?
A) By opening the radiator cap
B) By looking at the sight glass on the brake fluid reservoir
, C) By pressing the brake pedal and observing resistance
D) By checking the color of the brake fluid
E) By listening to the brake warning system
✓ Correct Answer: B - By looking at the sight glass on the brake fluid reservoir
EXPERT RATIONALE: The brake fluid level should be checked by observing the sight
glass (transparent panel) on the brake fluid reservoir. The fluid level should be
between the minimum and maximum marks on the sight glass. Low brake fluid can
indicate a leak or worn brake pads and is a serious safety issue. Opening the
radiator cap would give incorrect information about brake fluid, and other methods
listed do not accurately measure fluid level.
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
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━━━━━━━━
6. What does the brake warning light indicate on a commercial vehicle's
dashboard?
A) The engine is overheating
B) Low air pressure in the brake system
C) The battery needs charging
D) Oil pressure is low
E) The transmission is malfunctioning
✓ Correct Answer: B - Low air pressure in the brake system
EXPERT RATIONALE: The brake warning light indicates a low air pressure condition
in the air brake system. When this light illuminates, it means the air pressure has
dropped below safe operating levels, typically around 60 psi. This is a critical safety
issue that requires immediate attention. You should stop the vehicle safely and not
continue driving, as brake performance may be compromised. This light is essential
for maintaining brake system safety.
Questions & Answers | A+ Graded Study
Guide for Commercial Driver’s License
Success
TEXAS CDL GENERAL KNOWLEDGE EXAM QUESTIONS & ANSWERS | A+ GRADED
STUDY GUIDE FOR COMMERCIAL DRIVER'S LICENSE SUCCESS
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
• This comprehensive study guide contains carefully vetted multiple-choice
questions designed to prepare you for the Texas CDL General Knowledge Exam
with detailed EXPERT RATIONALE for each answer.
• Study systematically by reviewing each question, attempting the answer before
checking the correct response, and focusing on understanding the EXPERT
RATIONALE to master all CDL knowledge areas.
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
1. What is the primary purpose of a pre-trip vehicle inspection?
A) To identify mechanical defects that could cause a crash or breakdown
B) To wash the outside of the vehicle
C) To check the driver's logbook
D) To monitor fuel consumption patterns
E) To test the emergency warning system
✓ Correct Answer: A - To identify mechanical defects that could cause a crash
or breakdown
EXPERT RATIONALE: A pre-trip inspection is a safety-critical procedure required by
federal law. Its primary purpose is to identify any mechanical problems, defects, or
unsafe conditions with the vehicle before operation. Finding issues like brake
problems, tire damage, or lighting failures before driving can prevent accidents and
breakdowns. While other tasks may be part of vehicle maintenance, only option A
directly addresses the primary safety purpose of the inspection.
,━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━
2. When performing a pre-trip inspection, which component should you check
first?
A) The cargo area
B) The engine compartment
C) The tires and wheels
D) The lighting system
E) The mirrors and windows
✓ Correct Answer: B - The engine compartment
EXPERT RATIONALE: The engine compartment should be checked first during a
pre-trip inspection. This allows you to assess critical fluid levels, belt condition,
hoses, and overall engine health before starting the vehicle. Checking the engine
compartment at the beginning ensures you can identify serious problems early that
might prevent safe operation. A systematic approach starting with the engine helps
organize the inspection efficiently and safely.
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━
3. What is the minimum tread depth required for the steering axle tires of a
commercial vehicle?
A) 2/32 of an inch
B) 4/32 of an inch
C) 6/32 of an inch
D) 8/32 of an inch
E) 10/32 of an inch
,✓ Correct Answer: B - 4/32 of an inch
EXPERT RATIONALE: Federal Motor Carrier Safety Regulations (FMCSR) require a
minimum tread depth of 4/32 of an inch on the steering axle tires and 2/32 of an
inch on all other tires. Steering axle tires require greater tread depth because they
are critical for vehicle control and direction. Insufficient tread depth can cause loss
of traction, hydroplaning, and reduced steering control, especially in wet conditions.
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━
4. Which of the following is NOT a proper way to check your tires during a pre-
trip inspection?
A) Look for bulges or blisters
B) Check for uneven wear patterns
C) Feel the tire with your hand to estimate pressure
D) Look for cuts or damage
E) Check that all valve stems are present
✓ Correct Answer: C - Feel the tire with your hand to estimate pressure
EXPERT RATIONALE: Feeling a tire with your hand cannot accurately determine tire
pressure. Tire pressure must be checked using a proper tire pressure gauge. A tire
can feel firm while being underinflated, or it may feel soft when properly inflated. A
pressure gauge is the only reliable method to verify correct tire pressure. All other
options are valid visual inspection methods for checking tire condition.
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━
5. How should you check the brake fluid level in a commercial vehicle?
A) By opening the radiator cap
B) By looking at the sight glass on the brake fluid reservoir
, C) By pressing the brake pedal and observing resistance
D) By checking the color of the brake fluid
E) By listening to the brake warning system
✓ Correct Answer: B - By looking at the sight glass on the brake fluid reservoir
EXPERT RATIONALE: The brake fluid level should be checked by observing the sight
glass (transparent panel) on the brake fluid reservoir. The fluid level should be
between the minimum and maximum marks on the sight glass. Low brake fluid can
indicate a leak or worn brake pads and is a serious safety issue. Opening the
radiator cap would give incorrect information about brake fluid, and other methods
listed do not accurately measure fluid level.
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━
6. What does the brake warning light indicate on a commercial vehicle's
dashboard?
A) The engine is overheating
B) Low air pressure in the brake system
C) The battery needs charging
D) Oil pressure is low
E) The transmission is malfunctioning
✓ Correct Answer: B - Low air pressure in the brake system
EXPERT RATIONALE: The brake warning light indicates a low air pressure condition
in the air brake system. When this light illuminates, it means the air pressure has
dropped below safe operating levels, typically around 60 psi. This is a critical safety
issue that requires immediate attention. You should stop the vehicle safely and not
continue driving, as brake performance may be compromised. This light is essential
for maintaining brake system safety.
