Heavy weight capability and Durability made the wheel casters like the VXB005200C a must use, get your do it yourself object move around from our Toronto biz. Dia. Measured of the caster wheel in metric standard 200mm which is equal to 7.874" inch with imperial units. Sizes of the caster wheel is 50mm (1.969" inch). The Caster with the wheel from end to end is 240mm = 9.449" inch. Top Plate is the method of installing the caster to your equipment, dimensions are 100mm x 115mm with the holes distance of 75mm x 85mm. Low drag was achieved by a Cast iron core on a Cast iron tire spinning freely with a Roller bearing. Each caster wheel will carry the load of 661 lb and is Swivel type. The Temperature range is -40 to 180 F. FYI, you will need to buy the VXB005200C in order to get one :).