Abstract
Rolling resistance is the energy a tyre loses as it rolls, and it directly affects how much fuel a petrol or diesel vehicle consumes and how far an electric vehicle can travel on a charge. High-speed tyres, built to remain stable and durable at high rotational speeds, often involve design compromises that influence rolling resistance. This article examines the relationship between rolling resistance and fuel efficiency for high-speed tyres in the United Kingdom. It explains the physics, the factors that determine rolling resistance, the effect of speed, the UK regulatory and labelling framework, the economic and environmental implications, and the trade-offs between efficiency, safety, and durability. It ends with recommendations for drivers, fleets, manufacturers, and policymakers.
1. Introduction
Road transport is a major source of energy use and greenhouse gas emissions in the UK. Passenger cars, vans, and heavy goods vehicles together account for a large share of domestic transport emissions. Improving efficiency is therefore a priority for households that want to reduce fuel costs, for businesses that operate fleets, and for the government, which has committed to ambitious climate targets, including the phase-out of new petrol and diesel car sales and a transition to zero-emission vehicles.
Tyres are often overlooked in discussions about efficiency, yet they are responsible for a significant share of a vehicle’s energy consumption. Estimates commonly suggest that tyres account for roughly one fifth of a passenger car’s fuel use, with the exact figure depending on speed, vehicle type, and driving cycle. For a country with a dense motorway network, where a large proportion of mileage is driven at sustained speeds near the 70 mph national limit, understanding how tyres perform at speed is highly relevant.
“High-speed tyres” here means tyres with higher speed ratings, such as V, W, and Y, and tyres designed for performance vehicles, as well as standard tyres that are used on motorways at sustained speeds. These tyres must resist heat, centrifugal forces, and deformation at high rotational speeds, and these requirements influence their rolling resistance.
2. What Is Rolling Resistance?
2.1 Definition
Rolling resistance is the force that opposes the motion of a tyre as it rolls on a surface. It is not caused by friction in the sense of sliding, but mainly by internal energy losses in the tyre’s rubber as it deforms. It is usually expressed through the rolling resistance coefficient (Crr), which is the ratio of rolling resistance force to the load on the tyre. The force is approximately:
F = Crr × m × g
where m is the vehicle mass and g is gravitational acceleration.
2.2 Hysteresis: the dominant source
When a tyre rolls, the tread and sidewall are compressed as they enter the contact patch and recover as they leave it. Rubber is viscoelastic, so it does not return all the energy used to deform it. The difference is lost as heat. This hysteresis accounts for the large majority of rolling resistance in a typical passenger tyre. Other contributions include:
- Aerodynamic drag of the rotating tyre and wheel, which is small but increases with speed.
- Friction and micro-slip in the contact patch.
- Road surface effects, such as texture and roughness.
2.3 Typical values
For passenger car tyres, the rolling resistance coefficient typically lies between about 0.006 and 0.012, meaning that between 6 and 12 newtons of resistance arise for every 1,000 newtons of load. The best low-rolling-resistance tyres are at the lower end of the range, while some performance or winter tyres are at the higher end. The difference may look small, but across thousands of miles it produces a notable difference in energy use.
3. How Much Energy Do Tyres Use? A Worked Example
Consider a car with a mass of 1,500 kg and a rolling resistance coefficient of 0.010. The rolling resistance force is roughly 0.010 × 1,500 × 9.81, which is about 147 N, and it is nearly constant with speed (apart from a modest increase at higher speeds).
At 70 mph (about 31.3 m/s), the power needed to overcome rolling resistance is about 147 × 31.3, or around 4.6 kW. Suppose the car has a drag coefficient of 0.30 and a frontal area of 2.2 m², giving a drag area of about 0.65 m². Aerodynamic drag at 70 mph is about 0.5 × 1.2 × 0.65 × 31.3², which is roughly 380 N, and the power required is about 12 kW. In this example, rolling resistance accounts for roughly 28 per cent of the road load at 70 mph.
At 30 mph (about 13.4 m/s), rolling resistance power is about 2.0 kW, while aerodynamic power is only about 0.9 kW. Rolling resistance then accounts for roughly two thirds of the road load.
This example, which uses simplified assumptions, illustrates two important points:
- At low and moderate speeds, rolling resistance is the dominant resistive force.
- At high speeds, aerodynamic drag grows with the cube of speed in terms of power and takes over, so the share of rolling resistance decreases, although its absolute contribution remains significant.
Because of this, reducing rolling resistance is valuable across the whole speed range, but it matters most in urban and mixed driving, while for sustained motorway driving the gain is smaller in percentage terms though still worthwhile in absolute terms.
4. Factors Affecting Rolling Resistance
4.1 Tyre construction and materials
- Rubber compound: Compounds with high silica content and specialised polymers can offer low hysteresis while maintaining wet grip. Compounds designed for maximum grip, as in many high-performance tyres, tend to have higher hysteresis.
- Tread depth and design: Deeper tread has more rubber to deform and therefore higher rolling resistance. New tyres have higher rolling resistance than partially worn tyres, and a tyre’s resistance can fall by a noticeable amount as it wears, though safety margins also fall.
- Carcass and belt design: Lightweight, stiff constructions can reduce deformation. Sidewall design influences the amount of flexing.
- Width and aspect ratio: Wider tyres, common on performance cars, usually have a larger contact patch and higher rolling resistance and aerodynamic drag, although effects depend on design.
- Weight of the tyre: Heavier tyres store more rotational energy and may need more energy to accelerate.
4.2 Inflation pressure
Inflation pressure is one of the most important and controllable factors. A tyre that is under-inflated deforms more, increasing hysteresis and rolling resistance. As a rule of thumb, rolling resistance rises by a few per cent for each 10 per cent drop in pressure. A tyre that is substantially under-inflated can increase fuel consumption by one or two per cent or more, and it also wears faster and is less safe. Surveys in the UK and Europe repeatedly find that a considerable share of vehicles are driven with at least one under-inflated tyre.
4.3 Load
Rolling resistance is approximately proportional to load. Carrying extra weight, such as luggage, roof boxes, or tools, increases resistance and energy consumption. Heavier vehicles such as SUVs and electric cars have higher rolling resistance forces, even if the coefficient is the same.
4.4 Temperature
A tyre’s rolling resistance falls as it warms up, which is why short journeys show higher energy use. In cold weather, rubber is stiffer and has higher hysteresis, so rolling resistance is higher at the start of a journey. Winter tyres, with softer compounds and deeper tread, typically have higher rolling resistance than summer tyres. In the UK’s mild climate, this effect is moderate, but it matters for those who use winter or all-season tyres.
4.5 Road surface
Rough, coarse surfaces increase rolling resistance, while smooth asphalt reduces it. Wet roads add a small increase due to water displacement. The UK’s road network includes a mix of surfaces, from smooth motorways to rough local roads, and potholes and patched surfaces also increase energy loss and cause damage.
5. The Effect of Speed on Rolling Resistance
Rolling resistance is often assumed to be constant with speed, but in reality it increases with speed, especially at higher speeds. Several reasons contribute:
- More flexing per second: Higher RPM means more deformation cycles per unit time, and the tyre does not fully cool between them.
- Higher temperatures: Although higher temperature reduces hysteresis in the rubber, the more rapid flexing and the dynamic behaviour of the tread produce additional losses.
- Standing wave effects: At very high speeds, a wave pattern can develop in the tyre, producing a sharp rise in resistance and heat. This is rarely relevant within UK speed limits, but under-inflated tyres at motorway speeds may approach the conditions that promote it.
- Vibration and aerodynamic effects: The rotating tyre and wheel push air around, creating additional drag that grows with speed.
For tyres designed for very high speeds, manufacturers must ensure stability and heat resistance, and the means used, such as stiffer construction and reinforcing layers, can add mass and stiffness. This does not necessarily mean higher rolling resistance, because modern engineering can reconcile both goals, but there is often a trade-off.
6. High-Speed Tyres: Efficiency Trade-offs
6.1 The “magic triangle”
Tyre developers often describe a three-way trade-off between rolling resistance, wet grip, and tread life, sometimes called the magic triangle. Improving one tends to harm another. For high-speed tyres, further requirements, such as handling precision, stability, noise, and heat resistance, add extra dimensions.
- Low rolling resistance generally requires compounds with low hysteresis, but lower hysteresis can reduce grip, especially in the wet, since grip relies partly on energy dissipation in the rubber.
- High grip and stability at speed may require wide tyres and stiff sidewalls with soft compounds, increasing rolling resistance.
- Long life requires harder compounds or more tread rubber, which can raise resistance.
Advances in silica technology, polymers, and tread design have shifted this triangle, so that modern tyres can achieve better results across all three, but the trade-offs persist.
6.2 Performance tyres versus efficiency tyres
High-performance tyres, such as those fitted to sports cars and powerful saloons, are usually optimised for grip and handling, and they generally have higher rolling resistance than efficiency-focused tyres of the same size. By contrast, tyres marketed as “eco” or “low rolling resistance” are optimised for fuel economy. However, in the UK many drivers buy tyres with high speed ratings because their vehicle requires them, so improvements in the efficiency of this category would deliver real benefits.
6.3 Speed rating does not equal efficiency
A high speed rating indicates the tyre’s capability under test conditions, not its efficiency. Some high-speed-rated tyres achieve excellent efficiency grades, while others do not. Consumers should consult the label for each specific tyre.
7. The UK Regulatory and Labelling Framework
7.1 The tyre label
Tyres sold in Great Britain carry a label that provides information on fuel efficiency (rolling resistance), wet grip, and external noise. This system originated in EU regulation and has been retained and adapted in UK law following Brexit. The label uses a letter scale for fuel efficiency and wet grip, from A (best) to E (worst) in the current scale, and it shows external rolling noise in decibels with a wave symbol. It also includes pictograms for snow grip and ice grip where applicable.
Fuel efficiency classes are based on the rolling resistance coefficient measured under standard laboratory conditions. Differences between classes are meaningful. Official estimates under the earlier label suggested that moving from the lowest to the highest class could save several per cent in fuel consumption, though real savings depend on driving patterns and vehicle.
7.2 Other relevant rules
- Type approval and standards: Tyres must meet approval requirements based on UNECE regulations, which include limits on rolling resistance in some regulatory frameworks.
- Tyre pressure monitoring systems: New cars must be fitted with TPMS, which warns drivers of significant pressure loss and thereby helps prevent increased rolling resistance.
- Legal tread depth: The minimum is 1.6 mm, and tyre condition is checked during the annual MOT test for vehicles older than three years.
- Climate policy: UK policy aims to move to zero-emission vehicles, and tyres are increasingly recognised as part of overall efficiency, including their effect on EV range.
7.3 Limitations of the label
The label is based on laboratory tests under controlled conditions, typically at a single speed on a smooth drum, and it does not capture real-world behaviour such as variation with temperature, load, pressure, and wear. Also, only a limited range of grades is shown, so differences within a class can still be large. Independent tests by motoring organisations and magazines provide additional information about actual fuel consumption and rolling resistance.
8. Economic and Environmental Implications
8.1 Fuel cost savings
A rough rule often cited is that a reduction of 10 per cent in rolling resistance can improve fuel economy by around 1 to 2 per cent in passenger cars, with the effect depending on the driving cycle. For a driver covering about 7,000 miles a year, the saving may seem modest, perhaps tens of pounds per year, but for high-mileage drivers and fleets it becomes substantial. A van or delivery operator covering tens of thousands of miles annually can achieve meaningful savings across a fleet by choosing efficient tyres and keeping them properly inflated.
8.2 EV range
For electric vehicles, the effect on range is significant. Because EVs are heavy and have efficient drivetrains, tyres account for a larger proportion of energy losses. A more efficient tyre can add a noticeable number of miles to range, which is a valuable benefit as the UK EV fleet grows. Manufacturers now offer EV-specific tyres designed to reduce rolling resistance while handling extra weight and torque.
8.3 Emissions
Lower fuel consumption means lower carbon dioxide emissions. Across the UK’s large vehicle fleet, even small percentage improvements in tyre efficiency could amount to a significant reduction in emissions. This forms part of a broader strategy that includes vehicle electrification, lighter vehicles, and improved aerodynamics.
8.4 Tyre wear particles
There is a potential link between efficiency and wear: tyres that wear faster release more particles, which are an emerging pollution concern. Therefore, efficiency gains should not come at the expense of excessive wear. Policy attention in the UK and Europe is moving towards methods and limits for measuring tyre abrasion, which will affect future designs.
8.5 Cost-effectiveness
Efficient tyres may cost more to buy, but the energy savings can offset the price premium over the tyre’s life. The balance depends on mileage, fuel price, and tyre lifespan. Cheap tyres with poor efficiency and short life can have a higher total cost of ownership.
9. Safety Considerations
Efficiency must never come at the expense of safety. Wet braking and handling are crucial in the UK’s rainy climate, and a tyre with excellent rolling resistance but poor wet grip can be dangerous. Consumers should therefore examine both the fuel efficiency and wet grip grades on the label, ideally choosing tyres that perform well in both. Maintaining correct pressure is a rare case where efficiency and safety align: correct inflation reduces rolling resistance, improves handling, reduces wear, and lowers the risk of heat-related failure at motorway speeds. Likewise, replacing tyres at an appropriate time, rather than running them down to the legal limit, protects safety even if a worn tyre has slightly lower rolling resistance.
10. Recommendations
For drivers:
- Check tyre pressure at least monthly and before long motorway trips, using the figures in the vehicle handbook and adjusting for load. Always check when the tyres are cold.
- Compare the fuel efficiency and wet grip grades on the label before buying, and use independent test results.
- Choose tyres that meet or exceed the vehicle’s required speed rating and load index.
- Remove unnecessary weight and roof boxes when not needed.
- Maintain steady speeds on motorways and avoid hard acceleration, which wastes energy.
- Keep wheel alignment and balance in good condition.
For fleet operators:
- Use tyre pressure monitoring and regular inspection programmes.
- Specify low-rolling-resistance tyres where safe and appropriate, and analyse total cost per mile.
- Train drivers in efficient driving.
For manufacturers:
- Continue to develop compounds and constructions that reduce hysteresis without sacrificing wet grip and durability.
- Provide clear, honest information on real-world performance.
- Develop tyres for EVs with attention to low rolling resistance, low noise, and low wear particle emissions.
For policymakers:
- Maintain and strengthen labelling and market surveillance to ensure accuracy.
- Support public awareness campaigns on tyre pressure and efficiency.
- Improve road surface quality, since smoother roads reduce energy loss.
- Develop standards for tyre abrasion alongside rolling resistance.
For researchers:
- Study real-world rolling resistance of different tyre classes under UK conditions, including temperature, wet roads, and varied speeds.
- Examine the trade-offs between efficiency, wear, and safety for heavy EVs.
11. Conclusion
Rolling resistance is a key determinant of vehicle energy use, and tyres are a practical and relatively cheap place to improve efficiency. For high-speed tyres, the challenge is to combine stability, heat resistance, and grip at high rotational speeds with low hysteresis and low energy loss. In the UK, where motorway driving, wet weather, high fuel costs, and ambitious climate goals intersect, selecting efficient tyres and maintaining them properly can deliver savings in money and emissions, and extend EV range. At low and moderate speeds, rolling resistance dominates the resistive forces on a vehicle, while at motorway speeds aerodynamic drag takes a larger share, but tyre losses remain significant. The UK tyre label, together with independent tests, helps consumers make informed choices, though its limitations should be understood. Ultimately, the best outcome lies in tyres that balance efficiency with wet grip, durability, and low particle emissions, and in drivers who keep them correctly inflated and sensibly used. As vehicles electrify and regulation evolves, tyre efficiency will become an increasingly important part of the UK’s journey toward more sustainable road transport.