One problem related to tire valve has been reported for the 1998 Ford Expedition. The most recently reported issues are listed below.
On Sunday, June 1st 2008, I was traveling southbound on the highway 99 in my wife's 1998 Ford Expedition from fruitridge rd to florin rd. As I exited onto florin rd going westbound, I heard what sounded like plastic caught on the side. I pulled into the 76 gas station on florin road and east parkway to asses the damage. The valve stem on my nearly new goodyear eagle gt ii 285/50-20 tire had torn. The horror is that I decided to take my wife's truck and leave my 2002 Ford excursion at home that morning because it had my boat attached and I didn't want to move it. This incident could have resulted in extreme harm done to my wife and children. It cost me time and money to correct this problem.