NASCAR: Lug Nut or Valve Stem Issue?

Flat tires caused when valve stems have been knocked off by lug nuts during pit stops have been a recurring issue for teams this season. The #19 of Joe Gibbs Racing driver Carl Edwards, the #27 of Paul Menard (Richard Childress Racing) and more recently, the #4 of Kevin Harvick (Stewart-Haas Racing) are among those that have been affected by the problem.

According to some in the garage, the problem isn't that the lug nuts occasionally strike the stem during a tire change. Instead, it's how the stem is seated in the wheel that makes it easier to be knocked off. "I don't even know how to fix it," Rodney Childers, crew chief for Harvick, said after Sunday's race at Michigan International Speedway. "Definitely got to do something though." NASCAR.com