1. Which castor for which floor?
The selected role should match the nature of the soil in order to provide optimal performance. Here are a few suggestions:
concrete floor: polypropylene, polyamide (rather loudly), polyurethane (rather quietly), elastic rubber (quietly)
bright floor: rubber or other traceless castors
Tiled floor: several elastic or rubber castors
Carpet: rubber, polypropylene or nylon (PA)