Washington, Nov 19 (IANS) A new generation of 'green' tyres that will boost fuel efficiency without affecting safety or durability is in the pipeline.

They could help add an extra mile or two per gallon (3.

78 litres) to a car's fuel economy, says a new study, reducing the emissions of greenhouse gases in the process. Greenhouse gases like carbon dioxide are leading to global warming.

Chemical & Engineering News (C&EN) senior editor Alexander Tullo explains that rolling resistance, the friction that tyres encounter when rolling, are a major factor in a vehicle's fuel economy.

For years, tyre makers and their raw material suppliers have been eyeing lower rolling resistance as a way to boost fuel economy and promote a cleaner environment.

But they have been thwarted by a principle called the 'magic triangle of tyre technology'. It holds that an improvement to rolling resistance has to come at the expense of wet-road grip and durability.

That barrier is now falling, thanks to the development of new materials, including new forms of silica and nanomaterials.

These new materials include a nanogel that improves abrasion resistance, grip and rolling resistance of tyres as well as a newly-developed resin that helps tyres retain air longer, said a release of the American Chemical Society (ACS).

But there's a catch: Motorists still will have to keep tyres properly inflated to take full advantage of the new technology, the article notes.

These findings have been featured on the covers of the current issue of Chemical & Engineering News, (C&EN).