The force resisting the motion when a body rolls on a surface is called the rolling resistance or rolling friction. The rolling resistance can be expressed as F r = c W (1)where Fr = rolling friction (N, lbf)c = rolling coefficientW = normal force or weight of body (N, lbf)Rolling Friction Coefficients Some typical rolling coefficients: Rolling Friction 0.001 - 0.0025 steel wheels on steel rails 0.0015 - 0.0025 low resistance tubeless tires 0.005 tram rails 0.006 - 0.01 truck tire on asphalt 0.01 - 0.015 ordinary car tires on concrete 0.03 car tires on tar or asphalt 0.04 - 0.08 car tire on solid sand 0.2 - 0.4 car tire on loose sand Example - Normal car on asphalt The rolling resistance of a normal car 1500 kg on asphalt with rolling friction can be estimated like F r = 0.03 (1500 kg) (9.81 m/s2) = 441 N