veeretakistus

Veeretakistus, known in English as rolling resistance, is the resisting force that opposes the rolling motion of a wheel on a surface. It arises from permanent deformation of the wheel and contact patch, hysteresis losses in the tire, and microscopic sliding at the interface, along with bearing and structural losses in the axle and wheel assembly. In vehicle dynamics, veeretakistus is a component of tractive resistance, alongside aerodynamic drag and grade resistance.

The rolling resistance force Frr is commonly approximated as Frr = Crr × N, where N is the normal force (roughly the vehicle weight distributed on the wheel) and Crr is the coefficient of rolling resistance, which depends on tire construction, road surface, inflation, and temperature. Typical Crr values for passenger car tires on dry asphalt are about 0.01 to 0.02; larger for worn tires, softer surfaces, or lower inflation.

It increases with load and can vary with speed and temperature; higher inflation generally reduces Crr, while soft surfaces and poor alignment increase it. In practice, veeretakistus is a major factor in energy consumption for road transport, particularly at lower to moderate speeds, while aerodynamic drag dominates at higher speeds. Reducing veeretakistus through proper tire inflation, low rolling resistance tires, lighter components, and smooth road surfaces can improve efficiency and reduce fuel use.

See also: rolling resistance, tire design, vehicle efficiency.