DOT Inspector Vehicle Inspection Procedures 3 — Questions and Answers
Question 1: According to FMCSA regulations, what minimum tread depth is required for front steering axle tires?
- 2/32 inch
- 4/32 inch (Correct answer)
- 6/32 inch
- 8/32 inch
Correct answer: 4/32 inch
Front steering axle tires must have a minimum tread depth of 4/32 inch, while other axle tires require 2/32 inch.
Question 2: When inspecting cargo securement, what is the minimum number of tiedowns required for a single piece of cargo that is 10 feet long and weighs 4,000 lbs?
- 1
- 2 (Correct answer)
- 3
- 4
Correct answer: 2
Cargo up to 10 feet in length requires a minimum of 2 tiedowns regardless of weight, per FMCSA 393.106.
Question 3: Which lighting defect would NOT place a vehicle out of service during a roadside inspection?
- Non-functional required headlamp
- Turn signal on the rear that is inoperative
- A side marker light that is amber instead of red at the front
- A single non-required auxiliary light that is burned out (Correct answer)
Correct answer: A single non-required auxiliary light that is burned out
Non-required auxiliary lights that are inoperable do not constitute an out-of-service condition; only required lights must be functional.
Question 4: An inspector notices a hydraulic brake line has a bulge in the rubber hose under full brake application. What is the correct determination?
- Acceptable if the bulge is less than 1 inch in diameter
- Out-of-service condition (Correct answer)
- Requires repair within 15 days
- Acceptable until the next scheduled maintenance
Correct answer: Out-of-service condition
Any brake hose that bulges, swells, or shows signs of failure under pressure is an immediate out-of-service condition per FMCSA 393.45.
Question 5: During inspection of a combination vehicle, how far must the kingpin be from the trailer's rear axle(s) before kingpin placement requires review?
- The kingpin must always be within 18 inches of the front axle
- Kingpin location is irrelevant to weight distribution inspection
- Kingpin-to-rear-axle spacing affects bridge formula compliance (Correct answer)
- FMCSA mandates a fixed 48-inch kingpin setback for all trailers
Correct answer: Kingpin-to-rear-axle spacing affects bridge formula compliance
The kingpin-to-rear-axle spacing is critical for bridge formula compliance, which limits axle group weights based on distance between axles.
Question 6: What is the FMCSA requirement for reflective tape on the rear of a trailer manufactured after a certain date?
- All trailers regardless of date must have reflective tape
- Trailers manufactured on or after December 1, 1993 must have conspicuity tape (Correct answer)
- Only tank trailers require reflective conspicuity markings
- Reflective tape is only required on trailers over 26,000 lbs GVWR
Correct answer: Trailers manufactured on or after December 1, 1993 must have conspicuity tape
FMCSA 393.11 requires trailers 80 inches or more in width manufactured on or after December 1, 1993 to have retroreflective sheeting or reflex reflectors.
Question 7: When performing a walk-around inspection of a CMV, what should an inspector check at each wheel end location?
- Only tire pressure and tread depth
- Hub seal condition, lug nut tightness, and brake component visibility (Correct answer)
- Only lug nut tightness and wheel cracks
- Only tire sidewall condition and rim integrity
Correct answer: Hub seal condition, lug nut tightness, and brake component visibility
A thorough wheel-end inspection includes hub seal condition for leaks, lug nut security, and visible brake components including rotors, drums, and linings where accessible.
DOT Inspector Vehicle Inspection Procedures 3
According to FMCSA regulations, what minimum tread depth is required for front steering axle tires?