The Carlisle Polyurethane Flat Free Universal Fit Utility and Hand Truck Tire. They offer performance similar to pneumatic tires without the flats. Not sure what hub length or bearing size you need? This Universal Fit tire is designed to fit the majority of hand truck and other small equipment with these sizes: 4.10/3.50-4, 3.50-4, 4.10-4. Includes adapter kit of additional bearings and spacers to fit tire onto various types of utility equipment. Adapter kit includes the following items: (1) - 1/4" Spacers, (3) - 1/2" Spacers, (2) - 3/4" Ball Bearings (5/8" installed), (1) - 5/8" Axle Cap. 2 Pack bundle.