TIRE TEETH Participants compete in the first rugged terrain obstacle run on U.S. Army Garrison Grafenwoehr in Grafenwoehr, Germany, April 13, 2013. More than 670 competitors participated in the 13-kilometer, 13-obstacle race, which centered around Grafenwoehr's rugged terrain trail, a training resource designed to test the ability of small units to operate in a physically demanding environment. SHARE: Download: Full Size (0.07 MB) Credit: VIRIN: 165887-Z-TAL66-122.jpg Photo Gallery