DETROIT -- The federal government and Ford Motor Co. are investigating whether the automaker's decision to lower the recommended tire pressure on its Explorer sport-utility vehicle contributed to Firestone tire failures that are being examined in at least 62 deaths.
Those deaths, and hundreds of other cases under investigation, led Bridgestone/Firestone Inc. of Nashville, Tenn., to recall 6.5 million tires earlier this month.
The recall covers P235/75R15 size radial ATX and ATX II brand tires, as well as Wilderness AT tires of the same size made at a plant in Decatur, Ill. The 15-inch tires are mostly on Ford trucks and sport utility vehicles.
Ford recommended inflating the tires on its Explorer sports utility vehicle at below maximum levels to reduce the risk of the vehicle rolling over during a sudden turn, according to an internal Ford document. While reducing the chance of a rollover, lower air pressure puts tires at a higher risk for overheating and failing.
The recall has focused scrutiny primarily on the sometimes catastrophic tread separation of tires that were under-inflated. When a tire's pressure is low, more of its sidewall is in contact with the road. That can lead to cracking or peeling.
The October 1989 document showed the Explorer failed safety tests and was at risk for rollovers when equipped with tires inflated to 35 pounds per square inch. But subsequent tests found it did not have that stability problem when the tires were inflated to 26 psi.
Ford has recommended since the Explorer went on sale in 1990 that the tires be filled to the 26 psi level, but has said recently that a range of 26 to 30 psi was acceptable. Bridgestone has maintained that the 15-inch tires on Explorers should be filled to 30 psi.
Reports of the Ford document first appeared Sunday in The New York Times and the Washington Post.
Ford spokesman Mike Vaughn said Sunday he could not confirm information in the document, which was distributed to reporters by a Little Rock, Ark., lawyer who is suing Ford and Bridgestone/Firestone. Vaughn did say that tire pressure is not the issue with the recall.
Brainerd Dispatch ©2013. All Rights Reserved.