Rolling resistance is one of the parameters that the EU's Vehicle Energy Consumption Calculation Tool (VECTO) uses to measure fuel consumption and carbon dioxide emissions. Understanding how it is calculated and the wider impact it has on the European Union's environmental goals is particularly important for vehicle manufacturers who already have to comply with the corresponding emission caps. However, similar CO2 reduction measures are expected to be expanded, in which case they would also affect truck operators and fleet managers. The sooner the entire industry becomes acquainted with these regulations and upgrades existing equipment to comply, the better.
Rolling resistance is one of five forces – along with gravity, aerodynamics, inertia and mechanical friction – that must be overcome for a vehicle to move forward. In simple terms it is the amount of energy a tyre uses over a defined distance. Given rolling resistance is responsible for up to one-third of a heavy-duty vehicle’s (HDV’s) fuel consumption, reducing it goes a long way towards cutting CO2 emissions.
Currently, only truck manufacturers have to use the VECTO tool to determine and certify a new vehicle’s fuel consumption and CO2 emissions. Accordingly, only the original equipment tyres supplied to the truck manufacturers by Continental carry a VECTO certification. Once a new truck is delivered, the owners are free to change the tyres as they please, even if this change affects the vehicle’s fuel consumption, increasing its CO2 emissions and invalidating the VECTO certification in the process.
However, we expect that it is only a matter of time before truck operators and fleet managers are held to the same standards as vehicle manufacturers. Considering rolling resistance as an important factor in your purchasing decision will immediately impact your fleet’s fuel economy, but it will also prepare you for potential changes in EU legislation ahead of time.
Rolling resistance is measured in kilograms per ton. The lower the rolling resistance coefficient, the less fuel that a vehicle consumes and the lower its CO2 emissions will be. There are a number of factors that affect rolling resistance and need to be taken into consideration in the equation: the design, tread and pressure of the tyre itself, the load and distribution of the vehicle, the road surface, and the weather.
VECTO is software that uses simulation techniques to model an individual vehicle’s fuel consumption and CO2 emissions by assessing a range of data points, including rolling resistance. Other parameters VECTO measures include detailed information about the type and weight of the vehicle, its aerodynamics, engine characteristics, transmission efficiency and axle configuration.
VECTO is software that uses simulation techniques to model an individual vehicle’s fuel consumption and CO2 emissions by assessing a range of data points, including rolling resistance.
Vehicle manufacturers are required to input all the relevant data into VECTO. The tyre rolling resistance measurement is supplied by the tyre manufacturer at the point of sale. For trucks that use a combination of different tyres, the total rolling resistance – the sum of the rolling resistance of each axle on the tractor and trailer – should be used. The VECTO certificate differs slightly from the EU tyre label, which also measures rolling resistance. While the same standards are used for both, the EU tyre label has a range of 1 kg/t for each tyre (eg. 4-5 kg/t) but the VECTO certificate uses a single value (eg. 4.8 kg/t).
Once all the relevant data points have been inputted, VECTO calculates a score for each vehicle and collates a range of material for customers and manufacturers: a certificate and sales-related information for the former; certification and monitoring data for the latter.
Fleet managers are not (yet) required to use the VECTO tool or meet certification requirements, but understanding how it functions can support you in maintaining a more economic, sustainable fleet that is prepared for a carbon-neutral future – and for every step on the way to that goal. If you are curious about VECTO, want to find out how well your fleet would comply with current regulations and what effect a change of tyres would have, try our VECTO simulator for free here.