Schwalbe Billy Bonkers Tire - 26 x 2.1 Clincher Folding BLK Performance AddixSchwalbe Billy Bonkers Tire 26 x 2. 1 Clincher Folding Black Performance Addix. The Billy Bonkers tire is designed for pumptrack dirtjump and slopestyle riding. This lightweight tire not only rolls extremely easily it also ensures fun loving and agile riding. If tricks and jumps get messed up Billy Bonkers remains good natured forgiving even egregious mistakes. Designed for maximum traction on crushed gravel and hard dirt Finely divided blocks