Marathon 18x8.50-8" Flat Free Tire on Wheel, 3.25" Hub, 1" Roller Bearing 18x8.50-8" Tire. 18" Tire Diameter. 8.5" Tire Width. Flat Free Tire made of solid, polyurethane foam. Non-marking. Ribbed Tread. 3.25" Centered Hub. 1" Roller Bearing. Perfect on roofing equipment, lawn mowers, etc. 500 lb load capacity. Not for highway use.