DETROIT - Although many people wouldn't think so, the tires on concept vehicles are works of art.
Consider Goodyear's Aquatred tires, which started as a concept in the early 1980s, when they were carved by hand.
Or take a look at the Goodyear tires on the Batmobile used by OnStar in its advertising and see a unique design - bats and all.
Whether they are development or concept tires, early prototypes are hand-carved by tradespeople using induction-heated knives. Each tire takes about 24 hours to create.
Although Continental General Tire Inc. produces some concepts, most concept tires used in North America are supplied by Michelin North America Inc. or Goodyear, said Steve Lash, Michelin manager of concept development and innovation.
The people who carve the tires are 'craftsmen, artisans,' Lash said. 'Every one of those tires has to look exactly the same.'
How do you teach such an art?
'One groove at a time,' said William Egan, chief engineer of advanced original equipment product design at Goodyear.
Cheaper when handmade
Tire makers began hand carving tires for economic reasons. Creating a treaded tire mold can cost $60,000 to $80,000, Egan said.
Treaded tire molds are four to five times more expensive than smooth molds, and because the time to develop a new tire ranges from one to three years, several molds could be needed.
But there are instances when the laws of design won't accommodate the carving of a tire; it has to be molded. 'In carving you can only take away mass, you can't add it,' Lash said. Goodyear was the first tire maker to offer concept tires to automakers, in 1984 with two designs.
In 1991 it produced 26 new concept tire designs. By 1995 that had grown to 50 individual designs.
But since then, demand for new tire concepts has decreased. This year Goodyear developed only 27.
'Concepts and prototypes dropped back when all of the auto companies pared back, and we started getting competition,' Egan said. 'For many years, nobody did it but us.'
Competition for Goodyear got particularly heavy in the mid-90s when Michelin began producing its own concept tires.
Before its acquisition by Michelin in 1990, Uniroyal/Goodrich was producing concept tires in small numbers. In 1994 Michelin became involved 'in a big way,' Lash said.
While Goodyear outsources about 95 percent of the carving of its concept and development tires to several Akron, Ohio, mold model shops, Michelin does all of its tire design and carving in-house.
'These concept cars are relatively secret, and we wouldn't farm that out to anybody,' Lash said.
Carving new relationships
Michelin and Goodyear say concepts are a way to pursue new relationships with automakers.
'Goodyear has traditionally had Chrysler locked up, but we've made some inroads there a little bit,' Michelin's Lash said.
Michelin's run-flat PAX tires, on 22-inch wheels, were part of the package on the Jeep Willys concept vehicle unveiled in January at the Detroit auto show. The gray tires with green sidewall accents complemented the silver-colored dune buggy while demonstrating Michelin's venture into colored tire technology.
'The reason we're on some vehicles and not on others is trust,' Lash said. 'You start out talking, then you may get a sketch or a fax, and then you may see the clay model.'
While concept tires cost about $1,000 each, neither Goodyear nor Michelin passes on that cost to the automakers. 'We get a lot out of just being on the vehicle. We get to learn different trends,' Lash said.
'This isn't business for us,' Egan said. 'We're in there and talking to the people, working on these vehicles that could turn into a real production vehicle.'
Tire makers retain the rights to the tread designs, usually obtaining patents on them. But the original concept tires become a permanent part of concept vehicles, Egan said.
Themes dictate design
Vehicle themes dictate tire design. During the Detroit auto show, Johnson Controls Inc. revamped a van to show off its use of factory-installed Legos boards and other options catering to children and young families. The van included BFGoodrich concept tires with a chunky, Lego-looking tread for added impact.
Goodyear supplied concept tires with tread resembling rippling sand for the Chevrolet Borrego. It also supplied block-patterned tread tires for GMC's squared-off Terracross.
When it comes to concept tires, automakers are more concerned with aesthetics than performance, the tire makers said. 'Snazzy tires generate initial interest in concept vehicles,' Egan said.
Most concept tires and rims are made in sizes not approved by the Tire and Rim Association, sometimes getting as large as 23 inches in diameter. They are a sign of coming trends, the tire makers said.
'Normally, we wouldn't make some of these sizes, but if you look back five years at concept tires, and look at production vehicles two years ago, you knew it was coming,' Lash said.