Arnold Replacement Inner Tube for 4.80 x 4.00 Tire with 8 in. Rim 490-328-0006 - The Home Depot
Amazon.com: (2-Set) AR-PRO 4.80/4.00-8" Tire and Inner Tube Set - Universal Replacement Tires and Inner Tubes with 15.5" Outer Tire Diameter and 4.80" Tire Width - Fits on Dollies, Trolleys, Wagons, and
Amazon.com : TENKA 1 NEW REPLACEMENT WHEELBARROW INNER TUBE 4.80/4.00-8" OUT 16" : Patio, Lawn & Garden
Hi-Run Wheelbarrow Tire 4.80/4-8 4pr Stud in the Wheels & Tires department at Lowes.com