Things to know: Rolling Resistance
Published On 07-Jun-2016
Even for a person spending his life on a car or a bike, it takes some time getting used to the working and functioning of vehicles. The technical buildup of these vehicles is a mystery even to the best, and most proficient of drivers. The science of a motor vehicle is the most intriguing, but also the most essential for the ones working with them. The most basic know-how revolves around bringing a steady car into motion. The amount of energy it requires to bring and keep a vehicle in motion is distributed among its four wheels. This energy, consumed by the tyres for keeping the vehicle running, is known as rolling resistance.
Rolling resistance, in simpler language, is just the energy that is needed to keep your tyres rolling at a steady and straight pace. The vehicle's overall resistance is the group of multiple factors that leads to an impedance in forward motion, including even aerodynamic elements. And one of the elements among this overall resistance is rolling resistance, which occupies about a good 15% of it.
How does it work?
Basically, when tyres make contact with the road, energy is expended. These components are constantly stretching and bending in forward motion, under the weight of a vehicle, and this leads to friction between the tyre surface and the road. This friction and strain, in turn, needs a sustained flow of energy to be overcome and for the car to keep up in its smooth motion. It is this energy, specifically used for overcoming and going beyond the friction between the tyres and the roads, that is known as rolling resistance.
Factors affecting rolling resistance:
The energy required to keep the tyres rolling falls under the weight of a host of features. In general, all elements of a car play a part in accelerating or deteriorating the tyre's momentum. A few factors, in particular contribute in a major manner to the rolling resistance.
1) Tyre Pressure:
The tyre pressure or inflation is a crucial factor that affects the rolling resistance. This contributes in a big part to the resistance a tyre undergoes when biting through the streets. The higher the pressure, the lesser is the deformation or deterioration, and therefore, the easier the vehicle moves. Thus, the higher the tyre pressure, the lesser the rolling resistance.
2) Tyre Diameter:
Here is another important factor that impacts the effort tyres need to keep going- diameter. Tyres with smaller diameters have a greater deformation, or, in other words, a less 'round' format when running on the streets. Consequently, the strain met by such tyres is also high. As a result, the smaller diameter a tyre has, the higher its rolling resistance will be.
3) Tyre Construction/Material:
The material used in the making of a tyre is probably the most essential feature that affects its rolling resistance. Compounds that render sturdiness and durability are able to endure more and consume less energy. Compounds offering greater flexibility run on the street with ease and smoothness, thereby requiring less energy to keep them going.
Which one has higher, and which one has lower rolling resistance?
1) Radials with thinner sidewalls and shallower tread patterns generally have a lower rolling resistance. In addition to this, using special rubber compound to make them lighter, also helps in bringing down the energy required to keep them running.
2) New tyres have greater rolling resistance than used tyres as new tyres grip the road better. A higher grip would lead to a less swift ease in motion, thereby raising the rolling resistance. On the other hand, worn tyres provide a weak grip, but move with ease, thereby providing a lower resistance. The general rule is that the rolling resistance of the tyre drops over time. As the tyre ages, its grip and traction are weakened, and in turn, the rolling resistance is also brought down.
In conclusion, the tyre's rolling resistance has a powerful impact on a car with respect to its performance and handling. The most significant impact of the rolling resistance is on the fuel consumption. With a higher rolling resistance, the tyres require more energy to be kept in their motion and the fuel consumption is increased. Tyres with low rolling resistance require less energy and, in turn, contribute to bringing down the fuel consumption.
A higher rolling resistance provides a car with greater braking ability and, in turn, better handling. A lower rolling resistance, however, offers easy revving up for the vehicle can zoom to top speeds without much of a strain in its motion.