I have been using Nokian NBX 2.3's for 6 months. I am happy with the traction both wet and dry, but for the second time, my rear tire is losing side knobs. The first time, with over a dozen half cut off or dangling, Nokian replaced the tire. Kudos to their customer service. Maybe the tires are just not designed for the rocky terrain I ride. I am going to switch back to Continental Verticals-they wear faster, but I have never lost a knob.