Rolling Resistance

Rolling Resistance

Rolling resistance is a term used a lot in the tyre industry, and one you’re likely to come across when looking at details about various tyres. But what exactly does this term mean, and why is it important to consider when buying replacement tyres?

What is rolling resistance?

Also known as rolling friction or drag, rolling resistance refers to the force that resists the motion of an object when it rolls on a surface. In terms of a car tyre, when you are driving there are various physical forces that resist your car’s movement, such as air resistance, drag, and the properties of your tyres.

These forces are counteracted by the thrust generated from the engine, which propels the car forward when you drive.

The various factors that act against the car are combined to create what’s known as rolling resistance, which accounts for around 70% of the forces that act on your tyres. Rolling resistance, therefore, has a direct impact on how much energy is needed for the tyre to move.

What impact does rolling resistance have on your car?

There has been plenty of research on rolling resistance, including how various road conditions, tyres and other factors combine to increase or decrease its impact on your car.

As rolling resistance represents the forces your car has to work against to move, greater levels of rolling resistance mean that more energy is used by the car to get up to speed and stay there. Greater rolling resistance can have an impact on various elements of your car’s performance, particularly regarding fuel economy and handling.

If a vehicle encounters greater rolling resistance, it requires more energy to be used to get up to speed. This, of course, affects fuel consumption, with more fuel needed for a car encountering greater rolling resistance to drive the same distance as other vehicles.

Research suggests that greater rolling resistance may increase fuel consumption by up to 0.25 litres for every 60 or so miles. Although this may seem like a relatively small amount, when you consider that the average UK driver racks up around 12,500 miles a year, increased rolling resistance can have a major impact on fuel costs.

What factors affect rolling resistance?

Rolling resistance is influenced by several factors, many of which are incorporated into tyre design by manufacturers to create low rolling resistance tyres. Here are the most significant factors that affect rolling resistance:

Aerodynamic resistance

The aerodynamic resistance refers to the force of the air that surrounds your car. As the speed of the vehicle increases, aerodynamic resistance becomes greater in parallel, with this force representing up to 15% of the total rolling resistance value.

Weight of the vehicle

How heavy the vehicle is, as well as the load you are carrying, also has an impact, and the lower the weight of a car, the lower the rolling resistance is as well. Generally speaking, low-profile narrow tyres are usually lighter than wider options.

Tyre design

The height, tread pattern and compounds used in tyre design also affect rolling resistance as well. Shorter tyres are more rigid, and have lower rolling resistance, while using different rubber compounds alongside an optimised tread pattern can reduce rolling resistance by up to 60%.

Tyre pressure

Under-inflated tyres change the way that a tyre comes into contact with the road, which can increase rolling resistance by as much as 30%.

How to reduce rolling resistance

There are various ways that you can help to reduce rolling resistance through your driving style, car maintenance, and tyre choices.

As mentioned above, tyre pressure can have a significant impact on rolling resistance, and regularly checking and maintaining the right tyre pressure is hugely important as a result. When a tyre is correctly inflated, the optimum parts of the tyre come into contact with the road, and it is able to maintain its shape better. This will help to reduce rolling resistance, while also offering a wide variety of additional benefits too.

In terms of driving style, the effects of aerodynamic resistance is increased at higher speeds, and the faster a vehicle goes the more that the tyres will contribute to rolling resistance. This can be offset by following the speed limit, which will reduce the impact of rolling resistance on your tyres.

You can also lower rolling resistance by reducing the load in your car, as the higher the weight of a vehicle, the greater the levels of rolling resistance. With a bigger load and increased rolling resistance, the car requires more fuel and engine power to pick up speed.

In addition to using more fuel, this can also lead to various other issues over time. By lightening your load, and removing any unnecessary weight from your car, you can reduce rolling resistance, increase fuel economy, and reduce the damage from wear and tear over time.

Finally, you can also look at the rolling resistance marking on a new tyre by checking the labelling (which is indicated by the fuel efficiency table). Tyres are graded from A-G on their fuel efficiency, which is determined by their Rolling Resistance coefficient (RRC). The higher grade that a tyre has, then the lower the RRC is, indicating a highly-fuel efficient low rolling resistance tyre.

Rolling resistance is something that all vehicles face, as it is an inevitable part of the driving process. By taking a few key steps, however, you can reduce the impact of rolling resistance on your tyres, helping to improve fuel economy, prolong the life of your tyres, and ultimately, save money.

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Ratings from A-G
A = Best Fuel Economy

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Ratings from A-G
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