Work out rolling resistance instantly with clear inputs, formula shown and shareable results.
Rolling resistance is proportional to the load rather than to speed: F = Crr x m x g. A 1500 kg car with Crr = 0.012 loses about 177 N to its tyres whatever the speed, but the power that costs grows linearly with speed - 4.4 kW at 25 m/s. Aerodynamic drag overtakes it above roughly 60-70 km/h.
Rolling resistance
F = Crr x m x g
Power
P = F x v
About 0.006-0.010 for low-rolling-resistance car tyres, 0.012-0.015 for ordinary ones, 0.002-0.004 for a good bicycle tyre, and 0.001 for steel rail wheels.
Considerably. Under-inflation increases sidewall flexing and can raise Crr by 20-30%, which shows up directly in fuel consumption.