Vehicle Inspections

5 free sample questions of the 50 in this topic. The full set is in the app.

1. Question 1

   Federal rules say a CMV may not be driven unless the driver is satisfied that certain parts are in good working order. Which list matches the regulation?

   • A.Service brakes, parking brake, steering, lights, tires, horn, wipers, mirrors, coupling devices
   • B.Engine, transmission, exhaust, air conditioning, radio
   • C.Only the brakes and tires
   • D.Whatever the carrier's checklist includes
   Show answer & explanation

   Answer: A. Service brakes, parking brake, steering, lights, tires, horn, wipers, mirrors, coupling devices

   §392.7 lists the must-check items: service brakes (including trailer brake connections), parking brake, steering mechanism, lights and reflectors, tires, horn, wipers, mirrors, coupling devices, wheels and rims, and emergency equipment.

   Source: 49 CFR Part 392 — Driving of Commercial Motor Vehicles — §392.7(a) — Equipment, inspection and use

2. Question 2

   The minimum tread depth for tires on a truck's front (steering) wheels is:

   • A.2/32 inch
   • B.4/32 inch
   • C.6/32 inch
   • D.8/32 inch
   Show answer & explanation

   Answer: B. 4/32 inch

   Front wheels of a bus, truck, or truck tractor need at least 4/32-inch tread depth in a major groove; every other tire needs at least 2/32 inch. Don't measure on tie bars, humps, or fillets.

   Source: 49 CFR Part 393 — Parts and Accessories Necessary for Safe Operation — §393.75(b) — Tires, front-wheel tread depth

3. Question 3

   The minimum tread depth for tires OTHER than the front wheels is:

   • A.1/32 inch
   • B.2/32 inch
   • C.4/32 inch
   • D.5/32 inch
   Show answer & explanation

   Answer: B. 2/32 inch

   Non-steering tires need at least 2/32-inch tread groove depth measured in a major tread groove.

   Source: 49 CFR Part 393 — Parts and Accessories Necessary for Safe Operation — §393.75(c) — Tires, tread depth

4. Question 4

   Which tire condition makes a vehicle illegal to operate?

   • A.Tread depth of 6/32 inch on a drive tire
   • B.Body ply or belt material showing through the tread
   • C.A recapped tire on a rear axle
   • D.Slightly uneven wear across the tread
   Show answer & explanation

   Answer: B. Body ply or belt material showing through the tread

   No vehicle may be operated on a tire with body ply or belt material exposed, tread or sidewall separation, a flat or audible leak, or a cut deep enough to expose ply or belt.

   Source: 49 CFR Part 393 — Parts and Accessories Necessary for Safe Operation — §393.75(a) — Prohibited tire conditions

5. Question 5

   Regrooved, recapped, or retreaded tires are prohibited:

   • A.Anywhere on a combination vehicle
   • B.On the front wheels of a bus
   • C.On any drive axle
   • D.Only when carrying hazardous materials
   Show answer & explanation

   Answer: B. On the front wheels of a bus

   Buses may not be operated with regrooved, recapped, or retreaded tires on the front wheels — steering-axle failures there put every passenger at risk.

   Source: 49 CFR Part 393 — Parts and Accessories Necessary for Safe Operation — §393.75(d) — Bus front-wheel tire restriction

45 more Vehicle Inspections questions are in the app, along with explanations and flashcards for every one.

OnRoute is an independent study aid based on the federal CDL standards (49 CFR Part 383), the FMCSA Entry-Level Driver Training theory curriculum (49 CFR Part 380 Appendix A), and related Federal Motor Carrier Safety Regulations. It is not affiliated with, endorsed by, or sponsored by the FMCSA, AAMVA, or any state driver licensing agency. CDL knowledge tests are administered by your state, and state-specific requirements may vary — always consult your state's CDL manual.