Tire Science Non-Highway Pre-Filled Inner Tube for 20-Inch x 18-Inch Tires For use with 20" and 18" tires Non-highway replacement inner tube 18 x 8.5, 18 x 9.5, 20 x 8 inner tube for 8" rim Tire sealant formulation finds and seals leaks; seals punctures instantly up to 1/8" Prevents future leaks and can extend the life of older tires Universal valve stern and effective down to -25 degrees Farenheit