Tire Aging: Is NHTSA Ready to Make Policy?

Last month, at the Society of Automotive Engineers’ annual government-industry conference, a National Highway Traffic Safety Administration (NHTSA) safety standards engineer presented a summary of the agency’s tire aging work, which continues despite not producing any regulatory changes.

The issue that took center stage more than a decade ago, in the wake of the Ford Firestone rollover scandal. The deadly Firestone tires at the center of the controversy met the federal safety standards but nonetheless were de-treading at high rates after several years in service.  In 2001, Congress suggested that the agency consider the feasibility of a tire aging test, and the agency and Ford embarked on a series of experiments to create an artificial oven-aging test for tires. In 2005, the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users directed the Secretary of Transportation document NHTSA’s progress on tire aging research, and its findings and recommendations. The agency’s 2007 report to Congress did not make any policy recommendations, but did allow that it was “evaluating the feasibility of a regulation related to tire aging by analyzing the safety problem (tire aging as a significant causal factor in crashes) and potential benefits and costs of a requirement for minimum performance based on an aging method.”

Six years later, no policy and the tire aging docket NHTSA opened in 2005 is officially closed for comments. But the agency (and Safety Research & Strategies -- see SRS Tire Safety) continues to file the results of its tire age research periodically. (The most recent agency submission was in July 2012, a report entitled: “Tire Aging Testing Phase 5.”) Could NHTSA’s Dr. Merisol Medri’s SAE presentation herald the arrival of a rulemaking? Her Powerpoint was not released, (click here for a copy) but our ears perked up at this slide:

“Based on analysis of data from 2005-2007 including databases (NMVCCS, GES, CDS), 90 fatalities and over 3,200 injuries occurred annually as the result of crashes that were probably caused by tire aging or where tire aging was a significant factor.”

This statistic stands out against the agency’s numerical analysis offered in the 2007 Research Report to Congress on Tire Aging: “From 1994 to 2004, NHTSA estimates that about 400 fatalities, annually, may be attributed to tire failures of all types.”

Doing the rough math -- does this mean that about quarter of the annual tire-related fatalities are due to tire age? And, how did NHTSA arrive at that figure? Tire Identification Numbers (TIN) – the only way to discern a tire’s age – are not available in the public version of some of those datasets. (We are aware that NHTSA has begun to collect TINs for some sub-sets of crash data.) According to Medri the agency will be publishing a more detailed account of its research in a new report that will be published in the tire aging docket, at some unspecified time.

Roll Me Over – One More Time

The Society of Automotive Engineers resumed its ongoing boxing match over injury causation in rollovers at last week’s SAE Government Industry meeting. In Malibu’s corner was Wayne State and University of Michigan’s Transportation Safety Institute, presenting research supporting the theory of occupant diving as the mechanism of head and neck injury in rollovers – regardless of roof crush.

(For those of you who haven’t followed this 25-year-old scrum, Malibu refers to two sets of experimental rollover tests General Motors conducted in 1983 and 1987 on Chevrolet Malibus. Known as Malibu I and II, the tests were conducted to validate the theory that occupants don’t suffer head and neck injuries because the roof collapses on them, but because the force of the crash propels them into the roof. Over the years, automakers have clung to the Malibu results, despite crash data showing that the number of deaths and injuries in rollover accidents has risen disproportionately, with more than quarter of the accidents involving a serious roof intrusion.)

On the other side was NHTSA, arguing that roof strength is related to injury. It’s refreshing – if ironic – to see NHTSA champion a relationship between intrusion and injury. The agency is a late convert to this view; after years as an adherent of the Holy Gospel of Malibu.

Meanwhile, over at the Transportation Research Board’s Annual Meeting – also last week – research from less likely suspects supported the need for stronger roofs.

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