Automakers are spending hundreds of millions of dollars to squeeze the last erg of electric energy from a whole range of forthcoming electric cars. Expensive software controllers and astronomically costly bits of composite body pieces are part of the game plan for vehicles like the 2011 Nissan Leaf and the 2012 Ford Focus Electric.

But what about tires?

Michelin says with the right tires, it's easy to increase the range of an EV by an additional 10 percent--just by designing a new set of treads, as is entirely appropriate here, from the ground up. Which brings us to the Michelin EV tire prototype, which the company is promoting at this week's 2010 Challenge Bibendum in Rio de Janeiro.

The prototype isn't a reverse-engineered version of a tire built for a heavier, more performance-oriented, gasoline-powered vehicle; it's been designed to maximize the potential of a lightweight electric car, and it looks it. To fit the mission, the Michelin tire is resized so it's larger in diameter, but is narrower, almost skinny--almost retro.

Engineers explain the boost in diameter will generate less rolling resistance, while the slight side profile helps the tire cheat the wind (it doesn't seem obvious, but tires are a measurable source of aerodynamic drag--they behave like solid rectangular blocks even when rolling). The tire might also be more durable, since it makes fewer revolutions to go a certain distance, which ultimately could mean fewer tires in landfills and in the recycling bin.

Michelin also says its EV tire prototype also gives good grip, even in wet or foul weather--a big concern given the tire's relatively flat tread pattern and inherently different driving dynamics. And the EV tire could lead to more interior room in a vehicle penned without any legacy pieces, since the narrower tires and wheel wells could allow for more cargo or passenger space.

The company hasn't said if it's signed any manufacturers up for the experimental tire, but as they see it, in a new era of electrified vehicles, the hurdles to long driving range and low cost are many--and tires can be a cheaper range extender than the Nikes you're wearing right now.