The trial-and-error research approach can be frustrating and seem never-ending. One Continental technician, watching the recipe go into the industrial mixer, quipped, "This equals job security."
But it also leads to incremental breakthroughs that collectively reduce worldwide energy consumption and conserve finite natural resources.
When the slabs emerge from the mixing, they are cataloged and stored to await testing by other Conti technicians, who cut the slabs into a variety of shapes.
From some slabs, technicians create tiny tires barely a centimeter wide, which are tested for friction, rolling resistance and longevity. Promising recipes undergo further development.
Continental and other tire makers are responding to an urgent call by automakers for improved fuel economy. In the United States, automakers must comply with sharply higher targets for their corporate average fuel economy by 2016. They are scrambling for ways to add efficiency to their fleets.
Better tires are one of the fastest and easiest ways to boost fuel economy. One carmaker estimates that adding low-rolling-resistance tires to a light truck can improve the truck's fuel economy by 1 to 2.5 mpg. In contrast, shedding 125 to 250 pounds adds only 0.3 to 0.5 mpg.
Terry Connolly, General Motors Co.'s director of tire and wheel systems, attests to the gains accomplished by the research conducted by Continental and other manufacturers. He estimates that rolling resistance, a measure of energy lost while moving a vehicle, has dropped industrywide by about 15 percent in four years.
"Traditionally, this kind of efficiency would have come at the expense of dynamic performance," such as braking, handling, grip and noise, vibration and harshness, says Connolly, who works at GM's proving grounds in Milford, Mich. "But we've demanded and received the same level of performance from today's generation of low-rolling-resistance tires as we've had in standard tires."
Noting the research under way at Continental and other tire manufacturers, Connolly said: "We expect to see more improvement over the next three to five years, but I personally doubt it can match the recent improvements. Based on what our best suppliers are telling us, I'd expect to see rolling resistance drop another 6 to 9 percent."
Because tires consume about 20 percent of a traditional vehicle's energy -- and 30 to 40 percent for electric vehicles -- additional gains in tire technology could lead to overall fuel-efficiency increases of at least an additional 1 to 2 percent. That is gold worth finding for automakers -- and tire makers.