Joe Murray in the form of Kona has the National Tire Co. of Japan make to his design four tires that are foldable with Kevlar beads. The Equilibrium and Propulsion are both Black sidewall tires, made using Black rubberized casing fabric so their exposed tire casing will be Black in color but they do have a thin sidewall as a part of their tread stock. The Equilibrium, which is intended for front wheel use, relies on a tread pattern that repeats every 2 3/8" using complex angular blocks placed horizontally across the tire. Please look at the tread image because there is no simple way to describe it. We found the rubber in the Equilibrium durometer tested to a 69/A hardness. The Propulsion is designed for rear wheel use and is directional with an arrow on the sidewall to suggest the intended forward motion. The Propulsion has a tread pattern that repeats every 1 1/4". At the tire edges are two L-shaped blocks one ahead of the other, with the wide leg facing forward. Between the set of four L-shaped blocks in V- formation are 5 smaller blocks that have bases slightly broader than their tops. The smaller blocks are based on a rectangular shape. We found the Propulsion rubber also tested to a 69/A hardness. Though both the Equilibrium and the Propulsion are advertised as having 7mm high tread blocks, this is true of only the blocks at the extreme edge of the tread crown, the ones down the center line of the tire are just 4.5mm tall.