Umtanum Ridge 27.5" x 2.2" (650B x 55)Description The ultimate 650B bikepacking tire is designed for rides where you dont know what lies ahead. Umtanum Ridge a steep and lonesome ridge in the central Cascade Mountains. The Umtanum Ridges large and widely spaced knobs grip tenaciously when conditions get tough. On pavement, it rolls and corners like a slick thanks to its large and strategically placed knobs that dont squirm and always put the same amount of rubber on the road. The Umtanum