Slime Smart tubes are inner tubes that have been pre-filled with Slime to prevent flat tires for up to 2 years When a puncture occurs, Slime instantly seeks out and seals the puncture, up to 1/8 in. Smart tubes install like a regular tube The sealant inside is non-toxic, non-flammable and cleans up with water For use on utility carts, hand trucks, generators, wheelbarrows and equipment with 8 in. (4.80/4.00-8) tires