Magazine - 15/05/06
On the road

Michelin's "green tyres": a solution to reduce fuel consumption

 
In general, when people talk about saving energy and preserving the environment, the engine immediately springs to mind. And yet the tyres - the only contact between road and car - also play a crucial role.
 
 
There are currently 800 million vehicles in the world. In 25 years' time, this figure will have doubled: 1.6 billion vehicles will then be on the road throughout the world! This prospect compels us, from now on, to consider the preservation of energy resources and the environment as an absolute priority.
 
Since 1992, Michelin has been endeavouring to make motorists understand the importance of tyres from an energy point of view. In effect, the tyres alone are responsible for 20% of a car's fuel consumption and for over 30% of that of a heavy goods vehicle. Out of every five full tanks of fuel, one is consumed by the tyres' rolling resistance alone. On each revolution, the tyre deforms to follow the shape of the road. In deforming, the constituent materials of the tyre heat up and dissipate part of the energy transmitted by the engine: this is the rolling resistance phenomenon.
 
So the objective is clear: in order to reduce this rolling resistance as much as possible, vehicles must be equipped with a new type of tyre, a radial tyre with silica-based tread bands - the famous "green tyre". These tyres make it possible to cut fuel consumption by 3%, reinforce users' safety (by a stronger grip) and last as long as normal tyres.
 
If all the cars and HGVs in Europe were fitted with these low rolling resistance tyres, annual fuel savings would be 4.5 billion litres of diesel and 1.5 billion litres of petrol. Annual CO2 emissions would for their part be reduced by 15 million tonnes, i.e. the equivalent of what is absorbed by 600 million trees per year!
 
The environmental impact of "green tyres" since 1992 is enormous: with 400 million "green tyres" sold in Europe since then, this impact translates into a saving of 12 billion litres of fuel, and the prevention of 31 million tonnes of CO2 being ejected into the atmosphere (equal to what 1.2 billion trees can absorb in one year!).
 
The impact of the tyre on fuel consumption is proven by the use of under-inflated tyres. At 90 kph (56 mph), a tyre that is under-inflated by 1 bar compared to the recommended tyre pressure results in an excessive fuel consumption of up to 3%! An under-inflated tyre in effect generates poor distribution of pressure on the ground, the tyre grips less and wears faster; it is deformed, gets hot and absorbs an increasing proportion of the engine's energy. So, before heading off on holiday, don't forget to check your tyre pressure - besides, it's (usually) free! 
 
The latest model in the range, the Michelin Energy tyre, is currently the market's benchmark in terms of low rolling resistance tyres. Its longevity is between 20 and 40% higher than average (which means fewer products to recycle).
For HGVs, the Michelin A2 Energy "green" tyre makes it possible to cut hauliers' fuel costs by 6%. A very considerable reduction when you consider that a long-distance HGV consumes, on average, 35 litres of fuel every 100 km (62 miles). So, for a tractor or articulated lorry, fuel savings at the end of a year can offset the total cost of the vehicle's tyres!
 
Pictures © Michelin