What is Rolling Resistance?

Rolling resistance, often called rolling friction, is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface. It is caused mainly by the deformation of the object, the deformation of the surface, or both. In the automotive world, rolling resistance is a critical factor in fuel efficiency and vehicle performance.

How to Use This Calculator

To calculate the power required to overcome rolling friction, simply enter the total weight of your vehicle in kilograms and your current speed in kilometers per hour. Select the surface type most appropriate for your environment, or enter a custom Rolling Resistance Coefficient (Crr) if you have specific manufacturer data.

The Rolling Resistance Formula

The calculation uses two primary formulas:

1. Force (F) = Crr × m × g
Where Crr is the coefficient, m is mass in kg, and g is gravity (9.81 m/s²).

2. Power (P) = F × v
Where F is the force calculated above and v is the velocity in meters per second.

Factors Affecting Resistance

Several variables impact the Crr value. Tire pressure is the most significant; lower pressure increases deformation and thus increases resistance. Temperature, surface roughness, and tire material also play vital roles. High-efficiency tires are designed with specialized rubber compounds to minimize this energy loss, which can account for up to 15% of a vehicle's total fuel consumption.

Frequently Asked Questions

Q: Does higher tire pressure always reduce resistance?
A: Generally, yes, but only up to the manufacturer's recommended limit. Over-inflating can lead to safety risks and uneven tire wear.

Q: How does speed affect rolling resistance?
A: While the force of rolling resistance is relatively constant at low to moderate speeds, the power required to overcome it increases linearly with your velocity.