-Ruben designed his tires with some high tech and common sense ideas to make a better tire. They feature thick side walls, and a new material called "Silkworm" internally that helps to reduce flats and are pressure rated to 110psi. The rear versions feature a smooth street/park tread pattern . The fronts have an aggressive dirt bite but still roll smooth on street or park surfaces. He also decided to make them in bigger sizes to absorb hard impact landings. Available in black only. Choose sizes 20"x1.90" or 2.00" for the rear or 2.15" or 2.25" for the front.