August 09, 2013
Michelin has the tire menu for hungry ALMS teams at Road America
The Muscle Milk Honda team, one of the "Big Boy" teams in ALMS this season, is a technical partner with Michelin.
To appreciate the challenges for Michelin and its technical partner teams here at Road America, imagine heading to dinner with friends who can’t agree on what they want: Italian, Chinese, French food, or maybe a bratwurst?
Now, imagine that your friends are actually one race car and the food choices are Michelin race tires.
One of the sport’s fastest and most challenging circuits, the 4.08 miles of Road America puts teams, drivers and tires to a robust test of performance.
Road America is not just about going fast. According to Michelin motorsports technical director Ken Payne, each part of the 4.08-mile circuit places some unique demands on tires. As a result, many of the Michelin technical partner teams will use two different tire compounds and a few may even run three compounds at once.
Ten of the fourteen turns here are right handers, so Payne reports that many Michelin teams often choose a split approach with harder compound tires on for the left side of the car. “Choosing one tire solution to do everything here means that you will have slightly less than optimum grip at some places and increased wear elsewhere.”
Long, Fast Straightaways:
Road America features three very long straightaways, including the nearly 7/8th mile long uphill front straightaway. Teams want to be as fast as possible on the straightaways. That means minimizing drag or down force to maximize straight-line speed.
But, just as all good things must come to an end, so, too, do straightaways. Each of the three straights has its own attention getting braking zone and 90 degree turn waiting at the end, sometimes with elevation changes in the braking zone.
Arriving at the end of each straight at nearly 200 miles per hour with reduced down force; drivers suddenly need stable braking and the mechanical grip provided by the tires.
“The Road America circuit has 160 feet of elevation change from top-to-bottom and over 420 feet of elevation change per lap,” said Payne. “The elevation changes increase the load factor on the tires, especially when the elevation changes occur in and out of the braking and cornering zones. Those loads impact tire wear and durability.”
“Braking is very critical here and the secret to consistent braking performance is the tire,” said Payne. “The teams have minimized the aerodynamic down force so they are heavily dependent on the mechanical grip of the tire. Managing the load transfer as the car balance shifts and the car changes direction is critical. If the tire performance drops off, the braking becomes less consistent and that impacts corner entry as well.”
Payne believes that 3 of the 14 turns at Road America are determining factors as Michelin technical partner teams and drivers select tires from the Michelin menu, which typically offers three options of varying degrees of tire compound softness.
Turn 5, the first big left hander of the predominantly right hand circuit, is a heavy braking, downhill entry at the end of a long straightaway. “Some teams may choose to run a soft tire on the right front wheel position to maximize grip here,” said Payne.
The next big challenge is “The Carousel” at turns 9 and 10. “You have over 2000 feet of heavy cornering so the tires are heavily loaded and build significant heat here,” said Payne.
The final member of Payne’s Big Three corners is turn 12, the famed “Canada Corner,” a demanding test of driver confidence and car performance at the end of the third long straightaway.
“Klaus Graf of the Muscle Milk Honda team says ‘this is a track for big boys,’” said Payne. “You need a well-balanced car and confident driver to run these speeds lap after lap. That is why we try to give our teams options so they can maximize their total performance of braking, cornering, consistency and durability,” said Payne. “That is what wins races.”
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