These solid rubber wheels are molded of durable compounds designed for general purpose use. They are furnished with oiless sleeve bearings or straight roller bearings as listed below.
Solid Rubber Wheel(All Hard)-one-piece wheel of shatter-resistant rubber throughout. Nonmarking, non-sparking, easy oilling, will not develop -set- under static loads.

Solid Rubber Wheel-a softer rubber tread permanently molded to a hard rubber core. Recommended for light loads where noise is a factor or floors are rough, but capacity is more limited.
When a choice exists between anti-friction (roller) bearings and friction-type (oilless) bearings, operators of manually-propelled loads near rated capacities will appreciate the better rollability provided by roller bearings.