WASHINGTON - The Ford Motor Company is once again bedeviled by a tire safety issue. The National Highway Traffic Safety Administration says it has opened a preliminary evaluation of China-made tire valves in more than a million 2007 Ford vehicles, including the Edge, Fusion, and Lincoln MKX, after receiving 37 complaints from consumers. Such a move can sometimes lead to a safety recall.

Other vehicles included in the preliminary evaluation include the Mercury Grand Marquis and , Ford Escape, Expedition, Explorer and Focus, as well as the Lincoln MKZ.

'The original equipment snap-in tire valves may crack due to poor ozone resistance,' said NHTSA in documents on its Web site. 'Air leakage from a cracked tire valve may result in tire damage, which could affect vehicle control.'

The documents report no crashes, injuries or fatalities as a result of the valves.

The federal government notes that on May 15, it began investigating potential defects in some snap-in tire valves made for Dill Air Controls Products by Topseal Auto Parts, a subsidiary of the Shanghai Baolong Automotive Corporation. 'During the investigation, became aware that Topseal is also the original equipment supplier of snap-in low-pressure valve stems for some Ford Motor Company vehicles,' NHTSA said. The government notes that 23 of the 37 complaints said that 'more than one valve was found to be severely cracked or cracked and leaking and had to be replaced.'

The valves were already under investigation for their failure rate in the aftermarket.

Ford grappled with another tire safety issue in 2000, when Firestone tire failures, mostly on Ford Explorers, led to recalls and lawsuits.