With these oversized, rugged wheels, you can easily handle any surface with your walker. The 8" diameter aluminum reinforced wheels have the treads to cover cobblestone, dirt or grass. The easy-to-install set requires no tools and attaches in minutes for unlimited mobility. Includes two off-road wheels and two, oversized rear skis for gliding over smoother areas. Supports up to 250 pounds. Plastic. 8"Dia.