Analysis of Effects of Tire Tread Deterioration on Safety Impacts from Analysis of Inspection Data

Despite a long-term focus on passenger vehicle safety, there are still 38,000 vehicle-related fatalities annually. Some are the result of failure to maintain safety components of vehicles, such as brakes, tires, or headlights. Following National Highway Traffic Safety Administration (NHTSA) guidelines, 18 states have implemented periodic safety inspection programs where certified inspectors assess components, and owners are required to repair or replace deficient components. In the case of tires, when a tire’s tread depth falls to 2/32 of an inch, its stopping distance on a road becomes very high. Thus, this tread depth level was built into the safety inspection thresholds for tires. A social challenge is that in an annual vehicle inspection, if a tire passes at a level of 3/32”, it may fall below the safe (2/32”) threshold soon after the inspection. In an era of higher vehicle miles traveled (VMT) and reduced attention to maintenance, perhaps the thresholds set for the safety inspections should be higher than the ‘safe level’ to provide a buffer. Using 6 million safety inspection records from Pennsylvania from 2006-16 the authors calculate tread depth deterioration and annual VMT at the vehicle level. The authors estimate the ‘percent of vehicles at risk of having unsafe tires before the next inspection’ (using the 2/32” threshold) to be about 30%. The authors also estimate how that percent of ‘at risk vehicles’ decreases as the inspection thresholds are raised, and find an attractive threshold at about 5/32” where the percent of at-risk vehicles would be very low. Such changes could further reduce fatal and non-fatal accidents.


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Research Report
  • Features: Figures; References; Tables;
  • Pagination: 22p

Subject/Index Terms

Filing Info

  • Accession Number: 01709489
  • Record Type: Publication
  • Contract Numbers: DTRT-13-GUTC-26
  • Created Date: Jun 10 2019 3:19PM