Kunhua 14-pu-y-sz-16 4.00-6-inch Flat Free Wheelbarrow Tire - 4.5-inch Centered Hub(Two Sides Symmetrical) - 5/8-inch Ball Bearings - 13-inch Tire Diameter Flat Free Tire made of solid polyurethane foam,don't have to inflate it Providing the bounce and load handling characteristics similar to an air-filled tire with the benefit of never going flat 4.00-6" Tire. 13" Tire Diameter.4.5" Centered Hub(two sides symmetrical). 5/8" Ball Bearings Not for highway use 400 lb load capacity