Heavy Duty 8" X 2" Swivel Caster with Polyurethane Wheels and Brakes - 950lbs Capacity Each - Set of 4 for Tool Box, Workbench, and Industrial Equipment - Perfect for Warehouses, Workshops, and Garage Storage

These are quite sturdy. I used them on a set of steel horses I use outside. The horses are made out of 5 inch structural steel and 2x3 rectangular steel tube. With these casters, I can move the horses around on asphalt with about 700 pounds on them with no effort. In fact, they roll so easy, I have to set the brakes on the casters to keep them from rolling around too easily.