Tires may next factor in the Michelin Green X Challenge
As the Michelin Green X Challenge heads to the American Le Mans Series at Monterey, May 12, at Mazda Raceway Laguna Seca, officials of the Green Racing steering team are pondering the next step in the continued growth and development in the fourth season of America’s premier environmental motorsports competition.
The Green Racing steering team is meeting with tire makers here to discuss means to factor tire use into the formula that currently includes energy use, emissions, speed and efficiency. These officials include representatives of the U.S. Department of Energy, EPA, SAE International and the sanctioning International Motor Sports Association.
Tires affect energy use in two ways, according to Bob Larsen, senior technical manager of the U.S. Department of Energy’s Green Racing Initiative and a charter member of the Green Racing steering team.
“Passenger car tires can save energy by reducing the rolling resistance—which accounts for nearly 20 percent of the energy used to push a vehicle along the road—and by reducing tire use through extended tire life,” said Larsen.
In motorsports, it is in the second area, reducing tire use, that the Green Racing group sees significant opportunity for reducing overall energy use in a motorsports environment.
“A single set of four passenger car tires represents nearly 28 gallons of well-to-wheel (WTW) oil use,” said Larsen. The figure is significantly higher for race tires and since every car uses multiple sets of tires in each race the cumulative energy impact is larger than most people realize.
“From an energy efficiency and environmental perspective, reducing the number of tires used during a race can provide significant benefits,” notes Scot Elkins, COO of IMSA and ALMS. “Using fewer tires eliminates the raw material and the energy used both in the tire construction and in the manufacturing process. There are additional savings in the energy used in distribution and in recycling used tires. It adds up to an enormous gain.”
Extending tire wear and using tires for multiple stints is already an important part of American Le Mans Series races and race strategies.
Unlike other forms of motorsports, which permit tire changes to take place simultaneously with refueling, the ALMS and the 24 Hours of Le Mans do not permit tire changes while the car is refueled. As a result, tire changes typically add 12-14 seconds to a pit stop in the ALMS. The time spent at Le Mans, where only two crewmembers with a single air gun are allowed to perform tire changes, is more than 20 seconds for each four-tire change. The margin of victory at the 24 Hour race in 2011 was 13.8 seconds.
“Tires are incredibly important in the ALMS and at Le Mans. We have open competition with four different tire makers competing here,” said Elkins. “The tire makers are continuously developing new technologies in order to multi-stint. The ability to double-stint—use the same set of tires for two fuel loads--may well be a deciding factor in the race here this weekend.”
“The tiremakers are producing new technologies and innovations on the ALMS race track to take to their consumer tires,” Elkins said.
“We support the Green Racing group’s efforts to factor tire usage into the Michelin Green X Challenge,” said Silvia Mammone, Michelin motorsports manager. “Tires are an important part of energy usage and the technologies that enable us to reduce tire usage in races is already being transferred to our street tires. Last year at Le Mans, the race winning Audi prototype used just nine sets of our tires in the 24 hour race and was able to run five stints or over 454 miles on a single set of Michelin race tires. That would have been impossible without continued development of new technologies,” said Mammone.