Ford Focuses on Rear Wheels

Sept. 25 -- Recalled Firestone tires mounted on Ford Explorers and other Ford Motor Co. trucks appear to fail more often on the rear driver’s side than other locations.

The automaker is trying to find a reason for the tendency, butcontends the tendency does not undermine its contention that treadseparations cited in complaints are a tire problem, not a vehicleproblem.

Rear tire failures are more common than front tire failures,according to experts, and are harder for a driver to control. Theyare more dangerous in sport utility vehicles like the Explorer thatare more prone to rolling over than passenger cars. When a reartire fails, it tends to push the rear of the vehicle to one sideand a startled driver may set the vehicle into a skid by stompingon the brakes.

The database of Firestone complaints released by the NationalHighway Traffic Safety Administration shows that most Explorerrollovers have involved a rear tire failure, and a few more of theminvolved driver, or left, side tires than passenger side. The vastmajority of complaints about Firestone tread separations haveinvolved Explorers.

Trend Noticed Before

Keith Baumgardner, a tire consultant who is analyzing Firestonetires in connection with lawsuits against the tire maker and Ford,said he noticed the trend of left rear tire failures some time agobut didn’t pursue it. Of the 63 cases of tread separations onExplorers that he has examined, 27 involved the left rear tire and18 involved the right; the rest were on the front wheels or theirposition was not known, he said.

Ford spokesman Ken Zino said the company had seen a slight leftrear trend, and was running tests to search for a cause at itsArizona proving grounds. Ford did not provide its data on thetrend.

“In the absence of a root cause, this is only preliminaryengineering work and we’re going to have to do a lot more work,”Zino said.

Feeling the Heat

Another Ford spokesman, Mike Vaughn, said engineers wereinvestigating several theories, including whether the location ofthe Explorer’s fuel tank on the left side of the vehicle could putmore weight on that wheel. The rotation of the Explorer’s driveshaft might place more force on the left side than the right. AndAmerican roads might radiate more heat from the center of thepavement than they do from the edges, increasing the heattransferred to the driver’s side tires.