EVERY YEAR, AMERICANS TOSS OUT some 240 million tires, creating gridlock in the nation's landfills. At Used Rubber USA in San Francisco, Mandana MacPherson, 26, and Cameron Trotter, 30, are providing an environmentally fashionable afterlife for inner tubes of discarded car and truck tires.

MacPherson designs and Trotter markets rubber wares, which include purses, pouches, knapsacks, cycle saddlebags, belts and sandals, ranging in price from $10 to $180. "People know about the rain forests but not about piles of tires," says MacPherson. "[Our products] start out as inner tubes and end up as nice handbags. We're an example of what you can do with waste."

MacPherson has been getting mileage out of used tires since 1984. While taking art classes at the Rhode Island School of Design, she fashioned a lopsided book bag out of an old inner tube. Soon she and a classmate were peddling their retreads to shops in New England and New York. After graduating from Brown University in 1986, the Connecticut-born MacPherson moved to San Francisco, where she met Trotter, a California native and customer-relations official who became her sales representative. "They're fantastic products," Trotter says. "I knew they had potential."

Today, retail customers and rubberneckers are finding their way to the duo's tiny store on Haight Street. The company grossed $13,000 in its first year, 1989, but the partners expect to triple their business in 1991, thanks to deals with Fred Segal's Santa Monica boutique and Seventh Generation, a catalog of environmental products. To keep up with increasing demand, MacPherson and Trotter—who have become romantic partners as well—forage regularly for discards. Dumpsters, tire dealers, even shoulders of nearby freeways yield rich raw materials.

MacPherson cuts the inner tubes into strips, washes them and cuts them into patterns at the converted warehouse where she and Trotter live. An assistant helps her hand stitch and fasten the rubber pieces with rivets and washers. Most in demand are bags with brand names like Firestone, Michelin and especially Pirelli, the Italian manufacturer. "They call it the Gucci of rubber," says Trotter. But unlike designer leather, Used Rubber's bags are waterproof, stainproof and come with a lifetime guarantee. So there's no need for spares. And should your bag get damaged, Trotter promises, "You can always bring it in for an overhaul."