Don't you hate getting rid of old tires?

You have to pay to dispose of them, then they sit somewhere just taking up space. Now, however, tires are being recycled to make sidewalks. While I was pleased about the recycling aspect, I was primarily excited about the benefits for trees that rubber sidewalks provide.

The company is Rubbersidewalks Inc., headquartered in Gardena, Calif. Its trademarked "Rubbersidewalks" are made from tires mixed with polyurethane and colorant. Rubbersidewalks are in use around the country including in Seattle and Olympia.

The reason I'm telling you about rubber sidewalks in a gardening column is because one of their biggest selling points is the fact that they help avoid the problems tree roots create with traditional concrete sidewalks. As large trees grow, their roots often crack and push up concrete sidewalks, creating hazardous conditions. Remediation usually has been the removal of the roots and the costly replacement of the sidewalk. Tree root removal compromises the health of the tree and its structural integrity. Too often the trees, not just the roots, also are removed.

The manufacturers of Rubbersidewalks suggest their product will eliminate the need to significantly harm trees. These materials are easy for crews to remove so they can be lifted for periodic nondrastic root pruning.

The inventor of Rubbersidewalks, Richard Valeriano, tested them in Santa Monica, Calif. His idea was to use rubber paving because it would be flexible and bend when the roots grew. He found that the roots grew differently under the rubber paving. They were slower growing and had smaller tender offshoots. This is probably because the rubber material is porous, allowing water and oxygen to get to the roots. Water and air only get through concrete sidewalks at the seams.

Rubber sidewalks may work well in moderate climates like those in Western Washington, but what about in our area, with icy winters and hot summers? Rubber sidewalks heat up in the sun but reach a lower maximum temperature than concrete and retain less heat. They have not been used much in colder climates and are being evaluated for their endurance to sub-zero temperatures and snow plows. One problem for our area might be development of water lines (mineral deposits) from irrigation. This can be cleaned off if it's found to be objectionable. Graffiti also can be easily cleaned.

Other advantages to the pavers is that they're more resilient than concrete and asphalt, providing greater walking and running comfort. Softer than other paving, there also are fewer injuries caused by falls and they decrease the noise of pedestrian and wheeled traffic.

What about the price and maintenance? The installed cost is about twice that of concrete, but they have four times the life of concrete when used near tree roots. A crew of two, instead of four, can install them. They can be lifted for periodic root pruning, then replaced.

They save trees, which is what Lindsay Smith, president and CEO of Rubbersidewalks, intended when she started the company. \

As for those tires we throw out -- it takes two tons of rubber tire waste to produce 400 square feet of Rubbersidewalks.

* Marianne C. Ophardt is a horticulturist for the Washington State University Cooperative Extension Office in Benton County.