Rolling resistance coefficient

Definition

The rolling resistance coefficient (RRC) or coefficient of rolling friction between two surfaces is defined as the ratio of the rolling resistance experienced between the surfaces and the normal force between them.

If $C_{rr}$ is the rolling resistance coefficient and $N_{f}$ is the normal force, then the force of rolling resistance is $C_{rr}N_{f}$.

The rolling resistance coefficient is the analogue for rolling of what the coefficient of kinetic friction is to slipping/sliding. It is, however, about two orders of magnitude smaller.