The National Highway Traffic Safety Administration decided Aug. 31 to upgrade its probe from a preliminary investigation to a more intensive engineering analysis. It plans to announce the action today. The investigation involves 47 million tires made between 1991 and this year that are similar to the 6.5 million already recalled. The agency began investigating Firestone ATX and Wilderness tires in May, after reports that treads were peeling off the tires. Ill. Most of the recalled tires are on Ford Motor vehicles, primarily Explorer sport-utility vehicles.
Manufacturers usually agree to recall their products.
But the agency did issue a consumer alert about the tires. Firestone has since agreed to pay for replacement of the 1.4 million tires.