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CSA - Sample 5 Why's for Tire Tread Violations


A roadside inspection report for a motor carrier showed the following violation: §393.75(c): Tire – Other tread depth less than 2/32 of an inch.

The motor carrier will want to find out the root cause of this Vehicle Maintenance BASIC violation.

Question 1: Why did this event take place?

Answer: The driver did not use a tire depth gauge. Instead, he visually inspected the trailer tire during pre-trip and post-trip inspections. Because of this, it was not noted on the most recent post-trip inspections. In addition, the same driver was assigned to the vehicle for the past few months so no one else was involved in pretrip and post-trip inspection process.

Question 2: Why was this not discovered during the vehicle’s scheduled preventative maintenance?

Answer: The vehicle has not been in the shop for 3 months.

Question 3: Why didn’t the maintenance shop notice the wear 3 months ago?

Answer: The maintenance department saw the tire was at 3/32 inch the last time it was in.

Question 4: Why didn’t the shop schedule maintenance for the tires at 3/32 inch?

Answer: It had the decision point of 2/32 inch before it acted.

Question 5: Why did they have the decision point at 2/32 inch?

Answer: It’s the way it has always been done. No one ever questioned it.

Possible Solutions

What might be some solution(s) based on the safety management cycle and the root cause(s)?

  • Develop a policy and procedures that change the decision point to 5/32 inch for front tires and 3/32 inch for other tires.
  • Develop a policy and procedures to routinely schedule maintenance more frequently than once every 3 months.
  • Train drivers on proper pre-trip inspection procedures as they relate to measuring tire depth. Issue drivers a tire depth gauge.
  • Communicate the new policy to all departments involved (safety, maintenance, operations) so that trucks and trailers can be brought in for PM schedules using the new tire standard.
  • Monitor the results by assigning the role of reviewing maintenance records, roadside inspection results, and driver post-trip inspection reports.