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Michelin GTLM Insider: Taking it to The Streets

A look at Michelin’s tire evolution through the years at Long Beach…

Photo: Michelin

Photo: Michelin

There are no perfect new race cars. Virtually every new race car has an initial weak point and the streets of Long Beach can expose any shortcomings not evident in the first two races at Daytona and Sebring.

But for Chip Ganassi Racing and the new Ford GT, BMW Team RLL’s new BMW M6 GTLM, and Risi Competizione’s and Scuderia Corsa’s new Ferrari 488 GTEs, there is no time to waste in the fierce IMSA WeatherTech SportsCar Championship GTLM class.

Facing each other and the defending IMSA GTLM champion Porsche North America’s proven Porsche 911 RSR and the 2015 Le Mans, 2015 and 2016 Daytona and Sebring winning Corvette Racing Corvette C7.Rs, the competitive bar is incredibly high.

But, as IMSA’s only open tire class, the GTLM teams can and do work with their tire technical partners to identify initial challenges and develop their new cars to optimize and extract maximum performance. Perhaps that is why all have chosen Michelin as their respective tire technical partner.

Long Beach actually presents an interesting case study.

Photo: Michelin

Photo: Michelin

The Audi Struggle

Despite conquering many of the world’s racing circuits with ease, the powerful Audi R10 TDIs struggled mightily in their debut on the 1.968 mile-circuit through the streets of Long Beach in 2007.

Seeing the turbodiesel R10s navigate the tight, turn 11 hairpin leading onto the main straightway was a bit like watching a battleship turn around in a narrow canal.

Audi ended that inaugural American Le Mans Series Long Beach race in a miserable seventh place, finishing behind six Porsche and Acura LMP2 cars and trailing the winning Porsche Penske RS Spyder by over a full minute at the flag of the 100 minute event.

While Long Beach was the most extreme case, Audi’s struggles on street circuits continued throughout the year as the Porsche Penske RS Spyders also won at Houston and Detroit.

Photo: Michelin

Photo: Michelin

Michelin Tire Testing

Later that year, nearly 7,000 miles from Long Beach, Audi found a solution during a multi-day Michelin tire development test in Europe.

The Michelin/Audi tire testing process is highly disciplined. The driver leaves the pit box, completes an out-lap; three timed laps, the in-lap and then returns.

The car data is immediately downloaded and the precise amount of fuel used is replaced. The driver’s feedback is recorded as a new set of tires are installed. The engine is re-fired and the process is repeated up to 25 times per day.

To avoid influencing feedback, the driver receives no information on the tires. Each set is simply numbered. Sets of the reference tire are periodically reintroduced to the process to monitor the accuracy of the driver’s feedback.

Audi’s Allan McNish is a master of this process and his inputs were always highly valued by the team, and the Michelin engineers and tire developers.

“The first day of the test is to evaluate tire constructions with the second day focused on compounds,” said Ken Payne, technical director motorsports, Michelin North America. “Day three is for evaluating the most promising combinations of constructions and compounds on longer runs.”

Photo: Michelin

Photo: Michelin

The birth of Michelin “street soft” tires

During the first day of the Michelin test, McNish noted that a certain set of tires were exceptionally good on turn in. “We should set those aside; that construction could be really good on the street courses,” said McNish.

Michelin engineers took McNish’s input to heart. Upon their return, they prepared a single set of development tires with that construction and a soft compound tread. A Michelin engineer hand carried them on his flight to the next major test.

When the tires proved promising, Michelin produced additional sets and Audi introduced them to competition at St. Petersburg in early 2008. Marco Werner set a Friday qualifying time that only one IndyCar matched. In the race, Werner and Lucas Luhr’s Audi R10 TDi took the victory.

Michelin engineers dubbed the tire “the street soft”, and here at Long Beach, Luhr and Werner won again.

Following Audi’s withdrawal from the series, the “street softs” were no longer used.

Photo: John Dagys

Photo: John Dagys

Michelin “street soft” 2.0

In 2012, team owner Greg Pickett asked Michelin if they could develop a new “street soft” tire for his Muscle Milk HPD ARX-03a LMP1 car.

This time around Michelin engineers took a different tact. They went with a similar construction but a slightly different tread compound.

Pickett’s squad stunned the competition and the paddock by double-stinting the street softs on its way to victory at Long Beach and double stinted them again on the permanent circuit at Mazda Raceway Laguna Seca.

“By then we had been able to migrate our tires over half a range softer,” said Payne. “We still called them ‘street softs’ because of the construction, but we were using what we now considered a medium tread compound.

“People were shaking their heads at how we could possibly double stint super ‘soft’ tires on a permanent circuit.”

Photo: Michelin

Photo: Michelin

Street to Street

That combination of high levels of grip and extended tire life is extremely important in the development of Michelin tires for consumers as well as on the race circuit.

The Michelin Pilot Super Sport was Michelin’s first street tire to really benefit from the learnings here.

Through its experience in developing the internal architecture for the “street soft” tires, it became possible to equip Pilot Super Sport tires with an unusually-performant family of tread compounds to substantially raise the bar for UHP tires and become the standard by which all other products in the category are measured.

Later, even more aggressive Michelin Pilot Sport Cup 2 tires were developed using the same philosophy and making them a highly sought-after solution by OE carmakers for today’s “specialty” cars—such as the C7 Corvette Z06 with Z07 Performance Package, the Porsche 918 Spyder, Ferrari 458 Speciale, Ford Mustang GT350R, Porsche 911 GT3 and GT3 RS, AMG GT, the new Acura NSX, and the new Ford GT. The key attributes were derived from tires that Michelin developed for circuits like Long Beach.

Photo: Michelin

Photo: Michelin

Long Beach 2016

Now, as the WeatherTech Championship heads to Long Beach, Michelin has another new approach.

Its BMW Team RLL, Corvette Racing, Ford Chip Ganassi Racing, Risi Competizione Ferrari, Scuderia Corsa Ferrari and Porsche North America technical partner teams will rely on tires designed for specific types of North American circuits.

“Last summer we introduced a new tire designed for what we classify as ‘low energy’ circuits,” said Payne.

“We wanted to create a tire that came up to operating temperature sooner and delivered an exceptionally high level of grip for one full stint. That should be a really good combination for Long Beach.”

But that doesn’t mean that all of the Michelin technical partner GTLM teams will follow the same script. Michelin teams will have their choice of a “medium/cool” and a “medium/warm” temperature options.

“Long Beach is a funny race,” said Payne. “Through the years we have had teams win with a harder compound and with softs. We’ve had a team win with a double stint, and although the race is only 100 minutes long, we’ve had them win it with two stops instead of one.”

Winning on the streets of Long Beach is always hard. Having the right tires makes it a little easier.

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