May 10, 2016 · Rubber on Concrete – 0.35 to 0.45. Nylon on Concrete – 0.03 to 0.04. Polyurethane – 0.04 to 0.08. Rolling resistance of a Castor Wheel mounted machine or equipment is therefore the measure of the friction between floor surface and the tread of the Castors wheel. Consider a 102Kg (1000N) Trolley on a set of four Soft Rubber Castors sitting