Check your Tyre Pressures
Twenty per cent of a car’s fuel consumption, or one tank in every five, is used to overcome the rolling resistance of tyres, but this increases if tyres are under-inflated. For commercial vehicles the figure is even higher with a fully loaded HGV using one third of its fuel in overcoming tyre rolling resistance.
Low tyre pressure and the resulting increase in rolling resistance leads directly to higher fuel consumption. In a car, tyres under inflated by 15 psi (1 bar) lead to 6% greater fuel consumption. That’s an increase of £150 every year on a fuel spend of £2,500 per year.
A recent survey of a commercial fleet including vans, cars and lorries, indicated that the operator could save £65,000 in fuel costs each year, while reducing its carbon emissions by 117 tonnes, simply by adjusting tyre pressures across its fleet.
Despite the importance of tyre pressure for fuel economy, surveys repeatedly show that a large proportion of all vehicles are driven with under-inflated tyres. Research by Michelin suggests that poor tyre pressure maintenance is costing UK motorists more than £440million, wasting more than 370 million litres of fuel and pumping an additional 1 million tonnes of CO2 into the atmosphere.
All of this is before the cost of premature wear on tyres is taken into account.
It seems that neither the safety implications nor the fuel-saving benefits of proper tyre pressures are getting through to drivers.
Tyre rolling resistance, eco tyres and fuel economy
Tyre rolling resistance is widely misunderstood. It arises from the deformation of the tyres while in motion. The energy loss comes both from the deflection of the tyre sidewall and the compression and deformation of the tyre tread at the road surface. These deformations combine into a drag force which can be accurately measured and which is significantly affected by inflation pressure. Eco tyres help to reduce this by using a stiffer compound so the tyres deform less, but generally speaking this makes them less suitable for higher speeds, so there’s a trade-off between performance and fuel economy.
Tyre pressure monitoring saves fuel
A TyrePal system makes it easy to keep track of tyre pressures. Alerts can be set when any tyre falls below the required level, and the system will give an immediate alert if pressure is falling due to a puncture. Unlike many other systems, TyrePal sensors also measure temperature, so an alert is given if a tyre is over-stressed – a condition that can quickly lead to a permanently damaged tyre or even a blowout.