The world’s population stands at just about 7 billion people, who have to be moved around and fed. They are moved around wherever on wheels. There are wheels and castors for every application of transport. The wonderful train systems throughout the world, invented and largely installed by the British in their 19th Century pomp, use heavy steel wheels. These are actually flanged steel wheels and are tested daily for reliability and efficiency. Around our roads motor vehicles run on inflatable rubber tyred wheels and so it can be said that the world runs and moves about on wheels and castors.
But that's not the end for this vast population, which has increased from 2 billion in my own time and has to be fed. That is done mostly by farming. Farms throughout the world use wheels and castors. They have a variety of vehicles on rubber solid tyred wheels and inflatable rubber tyred wheels and use polyurethane tyred wheels and castors for trolleys, which are used around the solid floor barns. Interestingly certain schools around the world are now using a school farm, an instrument of both education and food production. Phoenix High School in the inner city of London pronounced this a success and are visited by other similar organisations for assessment of visibility. They have to move things around creating a need for wheels and castors of all descriptions. Hopefully they'll resist the temptation to make crisps and chocolate bars.
Please browse our Agricultural Castors.