Rolling Resistance

The resistance that occurs when a round object such as a ball or tire rolls on a flat surface.

The tyre is deflected as it enters the contact patch

The tyre is deflected as it enters the contact patch. Energy is dissipated in this deflection and is not recovered as the tyre recovers it′s shape as it exits the contact area.

Rolling resistance can be minimised by reducing the deflection of the tyre. One method is to increase the tyre pressure.

Where

F = Rolling resistance [N]
Crr = Coefficient of rolling resistance [dimensionless]
N = Force normal to road surface [N] = mass x gravity

 Crr
train wheel on rail0.001 to 0.0025
bicycle tyre0.0022 to 0.005
low rolling resistance car tyre0.006
ordinary car tyre0.01
car tyre on sand0.3

See also: Drag, Tyre, Tyre Rolling Radius, Vehicle Aerodynamic Drag.

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Subjects: Mechanical Engineering Transport