Locals who thought they had a new spring in their step might be surprised to learn the US capital city is trying out sidewalks made of recycled tires, officials say.

Tougher and more environmentally friendly than concrete, the sidewalks are made by a company cashing in on the 34 million used tires tossed into the trash in California each year.

Rubbersidewalks has put its non-slip product on the ground in some areas of US cities such as Seattle, Washington, San Francisco and Savannah, Georgia.

In Washington, "they have been installed … for a test. We'll keep an eye on it through the winter and see how they behave with the snow and the ice," said Wasi Khan, materials engineer at the city's Department of Transportation.

Though pricier than concrete, rubber walkways have their pluses because, as the roots of large trees grow, they can crack concrete. But rubber bends.

"Oaks roots … can crack the concrete after two years," Khan said, noting that the recycled sidewalks were "environmentally attractive."

They might go easier on joggers' knees, as well.