The Vulpine S is the fastest tire we make. Vulpine S is the latest race-focused addition to WTBs line of beloved gravel tires. Vulpine S is the gravel revamp of a proven semi-slick mountain tread with years of swift efficiency under its belt. The slick centerline decreases rolling resistance while its round tire profile is packed with short, tightly-spaced knobs to provide predictable cornering traction on hardpack terrain.