NASHVILLE, Tenn.—Following the lead of its Japanese parent, Bridgestone Corp., Bridgestone/Firestone in the U.S. is recommending a 10-year service life for tires.
BFS, however, said there is no scientific or technical data to justify the 10-year guideline. It also said it endorses the Rubber Manufacturers Association´s call for the National Highway Traffic Safety Administration to generate tire aging data and issue a consumer advisory countering the idea that tires have a hard-and-fast expiration date.
However, consumer advocate group Safety Research & Strategies in Rehoboth, Mass., said the tire maker´s announcement was a step in the right direction, but didn´t go far enough.
Bridgestone in Japan decided in September to follow the May 24 directive from the Japan Automotive Tire Manufacturers Association. The JATMA document said motorists should be encouraged to have their tires inspected after five years of use and replaced after 10 years.
"As time passes, the properties of the tires change," the directive stated. "Since the environmental and storage conditions, as well as usage methods such as load, speed and air pressure, influence the change of rubber properties, inspection is necessary."
At the same time, the JATMA warned that the 10-year recommendation was only a guideline, not a rule. Some tires may remain serviceable after 10 years, while others may not last that long, depending on the above-named factors, it said.
In an October technical bulletin to its dealers, BFS said it too was adopting the JATMA recommendation.
"Although (BFS) is not aware of technical data that supports a specific tire service life, we believe it is appropriate to follow the JATMA recommendation in the interest of further encouraging consumers to focus on the importance of maintaining and properly replacing their tires," the Nashville-based tire maker said.
Domestic tire makers´ view
The idea that tires should be removed from service after a set period generally is anathema to U.S. tire makers. The RMA and the Tire Industry Association reacted with dismay to the announcements by Ford Motor Co. and DaimlerChrysler A.G. last spring that they would start recommending customers replace their vehicle´s tires after six years of use.
On June 10, the RMA wrote NHTSA asking the agency to issue a consumer advisory outlining the factors that affect a tire´s service life. It also asked NHTSA to study the effects of aging on tires and generate data on aging. The agency has yet to answer the RMA.
NHTSA is working to develop an aging test to add to new tire safety standards, and the agency should issue a proposal on age testing sometime next year, an RMA spokesman said. But the test will be geared toward age endurance, not expiration dates, he added.
"You need to have some scientific basis to establish any sort of tire service life, and that doesn´t exist," he said.
Sean Kane, president of Safety Research & Strategies, said it is refreshing for a tire manufacturer to acknowledge that age degradation is a causal factor in tire failure. But he also said BFS defaulted to Ford and DaimlerChrysler as to the time when tires should be replaced for age.
"It sets up a conflicting image," said Kane, whose group´s clients include attorneys, engineering firms, supplier companies, media and government. "But ultimately I think they´ll advocate a six-year limit."
Kane also said it is contradictory for BFS to continue to support the RMA´s position.
"They´re the best ones to tell us when their customers should replace their tires," he said. "There´s no one date, and we never said there was. But there are some guidelines. Do we expect every tire to last the same period of time? Of course not. But the onus is on the manufacturers to tell us what the guidelines are."
Safety Research & Strategies has petitioned NHTSA for a six-year expiration date on tires and a requirement to place a non-coded date of manufacture on both sides of a tire. The agency has answered neither petition to date.