CDL General Knowledge TestDriving SafelyEasy
During a pre-trip inspection, you notice that your vehicle's tires are worn to the point where the tread depth is less than 4/32 inch on a steer axle tire. What is the correct action to take?
- AReplace the tire immediately before operating the vehicle.
- BReport the issue to dispatch and wait for their instructions.
- CInflate the tire to maximum pressure and monitor it closely.
- DProceed with the trip, but drive at a reduced speed.
Show answer & explanationAnswer & explanation
Correct answer: A. Replace the tire immediately before operating the vehicle.
Federal regulations mandate a minimum tread depth of 4/32 inch for steer axle tires. Operating a commercial vehicle with less than this depth is illegal and unsafe, requiring immediate replacement.
Why the other options are wrong
- B. While reporting is good, this is a 'no-go' item that requires immediate action, not just reporting and waiting.
- C. Inflating a worn tire will not restore tread depth and could exacerbate safety issues.
- D. Driving with insufficient tread depth is illegal and dangerous, regardless of speed.
Minimum Steer Axle Tread Depth
Federal regulations require steer axle tires on commercial vehicles to have a minimum tread depth of 4/32 inch. This ensures adequate traction and safety.
- 4/32 inch is the minimum for steer axles.
- 2/32 inch is the minimum for all other tires.
- Insufficient tread depth leads to poor traction and increased risk of hydroplaning.
Memory trick: Before you roll, check every hole, especially the steer's tread, or you'll be dead!