The Importance of Rolling Resistance for Fleets

Why tire rolling resistance is key to improve fuel economy and reducing CO₂ emissions

Tire rolling resistance is one of several attributes used to calculate a commercial truck's fuel efficiency. Given that it is responsible for up to one-third of a truck’s fuel consumption, understanding how rolling resistance works and what needs to be done to reduce it is critical to lowering carbon dioxide emissions. As well as helping the industry to fight climate change, the improved performance of low rolling resistance tires lets fleet managers and truck owners prepare for changing CO2 emissions standards.

What Is Tire Rolling Resistance?

Rolling resistance can be defined as the amount of energy a tire uses over a defined distance. It is one of five forces – along with gravity, aerodynamics, inertia and mechanical friction – that must be overcome for a vehicle to move forward. There are a number of factors that affect rolling resistance: the design, bead, belt, sidewall, tread and inflation pressure of the tire itself, the load and distribution of the vehicle, the road conditions, and the weather.

How rolling resistance influences fuel consumption

The most significant factor in reducing rolling resistance concerns hysteresis – the process that happens when a tire flexes as it meets the road surface, leading to an energy loss that inhibits forward momentum. Studies have shown that hysteresis accounts for as much as 85-90% of rolling resistance, so reducing it is a key objective. The majority of the energy that is dissipated through hysteresis occurs via a tire’s tread, largely as a result of the compound used. However, other factors, like tire pressure and alignment, vehicle weight, load and distribution, all have their part to play. The more tire pressure falls below its optimal level, for example, the greater the rolling resistance will be. If a tire on a 22.5" wheel is underinflated by 20% from its recommended inflation pressure, for example, the rolling resistance will increase by around 6% compared to a tire with the correct air pressure.

How hysteresis affects rolling resistance

Reducing Rolling Resistance: A Guide for Fleets

How tire manufacturers minimize rolling resistance

Tire manufacturers invest heavily in research and development to minimize rolling resistance, a key factor in fuel efficiency. Several techniques are employed:

Advanced Tread Compounds: These compounds are formulated to reduce friction between the tire and the road surface.

Optimized Tread Design: Careful design of the tread pattern can significantly reduce rolling resistance.

Low Rolling Resistance Casing: The tire's casing is designed to minimize internal friction and hysteresis, leading to improved rolling resistance.

How fleet managers can further reduce rolling resistance

While tire manufacturers play a crucial role, fleet managers can implement additional strategies to decrease rolling resistance and improve fuel economy:

Proper Tire Pressure: Ensuring that tires are inflated to the correct pressure is essential as underinflation increases rolling resistance and wear.

Tire Alignment and Balancing: Regular alignment and balancing ensure smooth tire rotation, reducing friction and wear.

Tire Selection: Choosing tires with low rolling resistance ratings can significantly impact fuel consumption.

Load Management: Avoid overloading tires, as this can increase rolling resistance and tire wear.

Regular Tire Inspections: Frequent inspections can identify potential issues such as uneven wear or damage.

Balancing Efficiency and Mileage When Choosing a Tire

Improving rolling resistance without compromising handling, grip and mileage is a delicate balancing act. Thanks to improvements in technology and production processes, however, reconciling these conflicting targets is possible. There are now a wide range of tires available that use innovative new compounds to decrease rolling resistance while remaining durable, offering high mileage and improving performance in a variety of real-world driving scenarios. The Conti EcoPlus HS3+, for example, has an advanced tread pattern with a low-void design, resulting in less deformation and higher mileage, while also delivering optimized handling, grip and wet performance ideal for navigating hilly, windy regional roads.

The Role of Tires in Reducing Carbon Emissions

Tires have always had a significant impact on everything from reliability and safety to running fleet costs and driver comfort. The fact that they have an important role to play in combating climate change by helping to reduce trucks’ fuel consumption and CO2 emissions is also hardly news. Accordingly, we have always taken inordinate care to produce safe, reliable products that offer the best combination of fuel economy, sustainability and durability.