The PU425-75 from Richmond Wheel and Castor Co. is a 100mm diameter polyurethane tyred cast iron centred wheel with a maximum capacity of 500kg and has a tyre width of 50mm.The following Richmond castors use this wheel (not necessarily with the same axle diameter) R4271, S4270.This wheel is designed to suit 3/4 inch (19.05mm) axles and this wheel is available for the following alternative axle size: 1/2 inch (12.7mm), 5/8 inch (15.87mm), 17mm, 20mm.