Most of a tyre’s environmental impact occurs during its actual use rather than during disposal as is commonly believed. This is due to the phenomenon of rolling resistance which affects fuel consumption and engine emissions. This find has prompted Michelin to develop new “low rolling resistance” technologies that save fuel. Michelin, which produced over 180 million tyres in 74 plants in 18 countries last year, has reduced the rolling resistance in its tyres by up to 30%; this translates to 5% lower fuel consumption.
As awareness of the importance of rolling resistance is still low among consumers, rolling resistance is rarely a criterion in purchasing replacement tyres. However, an increasing number of car-makers prefer low rolling resistance tyres particularly because they make it easier to comply with pollution-control regulations. With over a billion tyres sold every year, all of which will eventually be disposed of, tyres pose an environmental nightmare. Of the 400,000 tyres disposed of in France annually, only half are recycled; the rest end up in landfills, woods, rivers or other inappropriate places. This picture is replicated all over the world.
Things have improved in some countries following new legislations encouraging the recovery and recycling of used tyres. In France, a decree in 2002 stipulates that tyre makers must finance this process. Landfilling of used tyres has been outlawed in 11 American states and under a European Union directive, will no longer be allowed in Europe after 2006. Tyres can be recycled either to recover materials or to recover energy (by burning them as fuel). In material recovery, shredded tyres can be used as railway ballast (to reduce noise and vibration) or as light fill and drainage layers in roadway and public works construction.
Tyres can be a major source of energy. At around 30 megajoules per kg, their relatively high heat value is comparable to good quality coal, and sufficient to light a 60w bulb for about 40 days. A tonne of tyres produces the same energy as 0.7 tonnes of oil. Michelin has formed partnerships with several cement makers, many of which consume vast amounts of energy and thus use scrap tyres as fuel. In 2001, a joint-venture was formed with Lafarge in the UK, which over the past three years has burned some 50,000t of scrap tyres as fuel.