Marathon Flat Free tires provide the bounce and load handling characteristics similar to an airfilled tire with the benefit of never going flat, Flat free tire made of solid polyurethane foam, nonmarking, Ribbed tread, Perfect for residential wheepoundarrows, 3, 502, 508 replaces a 4, 006 tire, 13 tire diameter, 3Centered hub, 58 Ball bearings, Not for highway use, SKU: MTNI075