Birddog wheels come with metal valve stems, but we installed rubber stems because we like the way they give if they’re hit. Two valve stems per wheel ensure there will usually be a valve stem available, even if the other is under water or covered with muck. We will sometimes put a gauge on one stem while using the other to adjust pressure. The lug nuts have plenty of clearance, even enough for a star lug wrench. The outside raw aluminum abrasion ring with gauge holes is designed to be jammed into rocks, gouged, and abraded. The gauge holes tell us when a gouge is too deep and the wheel has been compromised.