The Colson Caster Commander HD heavy duty wheels are machined from a high impact polymer, which provides resilience and impacts strength. The wheels resist moisture and most chemicals. The slightly crowned tread profile allows the wheels to roll easily and better protects the floor. The Commander HD heavy duty wheels have a 2 inch tread for wheels with 4, 5, 6 and 8 inch diameters, and a 3 inch tread is available for 8 and 10 inch sizes. The wheels can support between 2,000 and 7,200 pounds each.