The X-CORE 6 is a rear wheelchair wheel designed to replace existing wheels on wheelchairs. These six-spoked wheels are hollow, seamless, lost-core composite wheels with smooth sealed bearings. They come standard with hard anodized aluminum handrims, Alshin polyurethane pyramid tires, and a choice of bearing sizes. OPTIONS: Plastic-coated or foam-coated handrims and Alshin polyurethane herringbone tread, rounded profile tires are available at extra cost. DIMENSIONS: The wheels are 24 x 1 inch. The bearings are available in a choice of half-inch, 7/16-inch, or 12 millimeter. COLOR: The handrims and spokes are black and the tires are grey.