Tire engineers are always working towards finding that sweet spot where upon there's more grip of the road by their tires, combined with the lowest possible rolling resistance. Goals such as optimum fuel economy or cutting a corner with the best possible line in-and-out, depend on factors such as rubber compound and tire construction. There's a certain uncertainty to the process, which makes any engineer feel frustrated; but that's because it's well nigh impossible to build a tire that meets the needs of all drivers.
"The future of the tire is about rolling resistance,” said Douglas Grass, an engineer with R&D for Bridgestone/Firestone, who works out of Phoenix, Arizona. “As technology improves, vehicles become more fuel efficient. Could we ever get to the point where tires have no rolling resistance? Probably not. But we can get very close to it.”
He was on hand to explain new tire technology to an assembled group of tire dealers, their sales associates and one journalist, in the parking lot of Emerald Downs racetrack. It is just outside of Auburn, Washington.
Emerald Downs is a horse racing track; however, one of the north parking lots was filled with orange parking cones making it closely resemble a SCCA (Sports Car Club of America) gymkhana. Several BMW 335i sedans were fitted with various examples of Bridgestone and Firestone tire technology. Call it a rolling classroom as it was just that; but it was also much more visceral than most classroom experiences.
It was a cool day in late spring and what constituted the track had been treated to additional wetness; to heighten the learning experience, by both Mother Nature and track hands.
Most fuel efficient tires offer 20 to 30 percent lower rolling resistance (according to Grass). That translates into a two to three percent fuel efficiency improvement on an automobile that might otherwise obtain 30 miles-to-the-gallon.
But due to the proposed tighter minimum fuel requirements for auto makers, tire engineers such as Grass are feeling more strain then a tire at one G of cornering. Essentially, he said, the NHTSA (National Highway Safety Administration) is mandating fuel efficiency.
The challenge that engineers such as Grass have to meet can reap big rewards with small improvements. If 50 million tires were produced for American consumption, and those tires had reduced rolling resistance of just three percent, it would translate into 33,238,125 gallons of fuel and the production of 308,682 fewer CO2 emissions; according to a presentation made the morning of the Drive and Learn event.
But if you're wondering how tires would be configured that could meet that three percent threshold, there's a clue in something that Grass told attendees to this event; who tried to guess what would offer the least rolling resistance. The answer was a rail car wheel, since it has a low control patch, the mass is constant and the turn that needs to be negotiated is a broad sweeping turn. - Terry Parkhurst
