Rolling Resistance Calculator

Rolling resistance is the friction force that opposes the motion of a wheel as it rolls on a surface. It is caused by the deformation of the tire and/or the road surface at the contact patch, generating heat and absorbing energy. Unlike sliding friction, rolling resistance does not depend on tire size or contact area — only on vehicle weight and the rolling resistance coefficient (Crr).

The primary cause is the deformation (hysteresis) of the tire material as it repeatedly compresses and recovers at the contact patch. Secondary contributors include road surface roughness, tire inflation pressure (lower pressure = higher rolling resistance), temperature, and speed. Harder tires on smooth surfaces have the lowest rolling resistance.

Rolling resistance force (RR) is calculated using the formula RR = Crr × N, where Crr is the dimensionless coefficient of rolling resistance and N is the normal force (the vehicle's weight component perpendicular to the road, N = m × g × cos θ). This calculator applies that formula automatically once you input weight, Crr, and incline angle.

For a standard car tire on asphalt, Crr typically ranges from 0.008 to 0.015. High-performance low-rolling-resistance tires can achieve Crr values around 0.006–0.008. Bicycle tires on smooth surfaces can go as low as 0.001–0.003, while off-road tires on sand or mud can exceed 0.03.

Interestingly, tire size (diameter or width) has very little direct effect on rolling resistance force — the dominant factors are vehicle weight, tire material and construction, inflation pressure, and surface type. Wider tires may have slightly lower rolling resistance per unit load in some cases, but the differences are small compared to Crr variations between tire compounds.

Rolling resistance directly consumes engine power to overcome. The power loss equals the rolling resistance force multiplied by vehicle speed (P = RR × v). At highway speeds, rolling resistance and aerodynamic drag are the two dominant fuel consumption factors. Reducing Crr by switching to low-resistance tires and maintaining proper tire pressure can noticeably improve fuel economy — typically 1–4% per 10% reduction in Crr.

On an inclined road, the normal force pressing the tire onto the surface decreases slightly as the angle increases (N = m × g × cos θ), which marginally reduces the rolling resistance force. However, climbing a hill introduces a much larger gravitational force component (m × g × sin θ) that dominates energy consumption on steep grades. This calculator accounts for incline in the normal force calculation.

The most effective measures are: (1) inflate tires to the recommended pressure or slightly above, (2) choose tires with a low Crr rating (look for fuel-efficiency labels), (3) use harder compound tires suited to smooth road surfaces, and (4) avoid overloading the vehicle. For cyclists, switching from knobby to slick tires on smooth roads can cut rolling resistance by 50% or more.