From Jayski.com.

Tire Air Pressure Tricks? A number of stock-car crews have been playing with tire tricks the past year, trying to prevent excessive air pressure build-up and improve handling over long runs. Two of the tricks have been installing illegal air-pressure bleeders in the valve stems, and the drilling of very tiny holes in the sidewalls, which is not specifically illegal. So when NASCAR officials confiscated Clint Bowyer's left-front tire at Martinsville after Saturday's Busch race, there were a lot of questions in the Nextel Cup garage at Pocono Speedway. But Mike Dillon, the director of team operations for Bowyer's car owner, Richard Childress, said that it was much ado about nothing. "Our left-front was leaking," Dillon said. "It was a valve stem leaking, but it was leaking at the rim, a bad seal or just not tight. A lot of people have been experimenting with bleeders, and I know there are guys drilling holes in sidewalls, too, to control the air. But if you wanted to use a bleeder at Martinsville, you'd want your left-rear to bleed.I don't think anything will come from it. We've talked with our crew chiefs, and they assured us there wasn't anything going on." Crew chiefs say that some tires have such naturally thin sidewalls that, even without doctoring, if they were submerged in a big vat of water, air would bubble out from a number of areas. "I had a tire at Michigan that actually lost seven pounds of air during a tire run, instead of having an air pressure build-up," one team manager said.(Winston Salem Journal)(7-25-2006)