Marathon Universal Fit Pneumatic (Air-Filled) 14.5-inch Tire and Wheel Assembly, Replacement for 4.80/4-8; 4-8; 4.80-8; 4-6; 3.50-8, Wheelbarrow/Cart Use, Castle Tread in the Wheels & Tires department at Lowes.com
Amazon.com: AR-PRO 4.80/4.00-8" Flat Free Tire - 14.5”D x 3.2”W Universal Solid Wheelbarrow Tire with 3” Hub and 5/8” Bearings – Extra Adapter kit includes 3/4” Ball Bearings, 1” and 1/2” Nylon
Buy the Ames FFTKBCC Knobby Solid Wheelbarrow Tire, Flat-Free ~ 8" | Hardware World