CDL GENERAL KNOWLEDGE FINAL
TEST COMPREHENSIVE STUDY GUIDE
1. What is the minimum tread depth required for steering axle tires on a commercial vehicle?
A. 2/32 inch
B. 4/32 inch
C. 6/32 inch
D. 1/32 inch
Answer: B
Conceptual Explanation: Federal regulations require steering axle tires to have at least
4/32 inch of tread depth. All other tires require at least 2/32 inch.
2. When performing a pre-trip inspection, what is a sign of potential wheel or rim problems?
A. Mismatched tire brands on the same axle
B. Tire pressure at 100 PSI
C. Valve stem caps being made of metal
D. Rust streaks around the lug nuts
,Answer: D
Conceptual Explanation: Rust streaks around lug nuts may indicate that the nuts are
loose, which can lead to a wheel coming off during transit.
3. Which of the following emergency equipment items is NOT mandatory for a commercial
vehicle?
A. Three reflective triangles
B. Spare electrical fuses
C. A first-aid kit
D. A fire extinguisher
Answer: C
Conceptual Explanation: While recommended, a first-aid kit is not federally mandated for
all commercial vehicles, unlike fire extinguishers, triangles, and fuses.
4. How far ahead should a driver look while driving at highway speeds?
A. 5 to 8 seconds
B. 12 to 15 seconds
C. 20 to 25 seconds
D. 30 seconds
Answer: B
, Conceptual Explanation: CDL manuals recommend looking 12 to 15 seconds ahead, which
is about a quarter-mile on the highway.
5. What is the ‘formula’ for determining following distance for a vehicle over 40 feet long
traveling at 40 mph?
A. 4 seconds
B. 8 seconds
C. 6 seconds
D. 5 seconds
Answer: D
Conceptual Explanation: The rule is 1 second for every 10 feet of vehicle length, plus an
additional second if traveling over 40 mph. For a 40ft truck at 40mph, it is 4 + 1 = 5
seconds.
6. When driving in heavy fog, which light setting should you use?
A. High beams for maximum visibility
B. Parking lights
C. Four-way flashers only
D. Low beams
Answer: D
TEST COMPREHENSIVE STUDY GUIDE
1. What is the minimum tread depth required for steering axle tires on a commercial vehicle?
A. 2/32 inch
B. 4/32 inch
C. 6/32 inch
D. 1/32 inch
Answer: B
Conceptual Explanation: Federal regulations require steering axle tires to have at least
4/32 inch of tread depth. All other tires require at least 2/32 inch.
2. When performing a pre-trip inspection, what is a sign of potential wheel or rim problems?
A. Mismatched tire brands on the same axle
B. Tire pressure at 100 PSI
C. Valve stem caps being made of metal
D. Rust streaks around the lug nuts
,Answer: D
Conceptual Explanation: Rust streaks around lug nuts may indicate that the nuts are
loose, which can lead to a wheel coming off during transit.
3. Which of the following emergency equipment items is NOT mandatory for a commercial
vehicle?
A. Three reflective triangles
B. Spare electrical fuses
C. A first-aid kit
D. A fire extinguisher
Answer: C
Conceptual Explanation: While recommended, a first-aid kit is not federally mandated for
all commercial vehicles, unlike fire extinguishers, triangles, and fuses.
4. How far ahead should a driver look while driving at highway speeds?
A. 5 to 8 seconds
B. 12 to 15 seconds
C. 20 to 25 seconds
D. 30 seconds
Answer: B
, Conceptual Explanation: CDL manuals recommend looking 12 to 15 seconds ahead, which
is about a quarter-mile on the highway.
5. What is the ‘formula’ for determining following distance for a vehicle over 40 feet long
traveling at 40 mph?
A. 4 seconds
B. 8 seconds
C. 6 seconds
D. 5 seconds
Answer: D
Conceptual Explanation: The rule is 1 second for every 10 feet of vehicle length, plus an
additional second if traveling over 40 mph. For a 40ft truck at 40mph, it is 4 + 1 = 5
seconds.
6. When driving in heavy fog, which light setting should you use?
A. High beams for maximum visibility
B. Parking lights
C. Four-way flashers only
D. Low beams
Answer: D
