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Michelin Memories: 2009, Acura’s ‘Square’ Tire Revolution

A look back at when Acura and Michelin introduced wide-front tires on its LMP1 car…

Photo: Rick Dole/Highcroft Racing

While Audi and Peugeot were the dominant forces in LMP1 competition, a bold design concept gave Acura the edge in tire performance throughout the 2009 American Le Mans Series season.

Following two years in LMP2, the automaker stepped up to the top prototype class with the innovative Acura ARX-02a, which featured the introduction of Michelin’s “square” tire fitment.

The Wirth Research-designed car was built to run the same sized rear tire on all four corners, a first in modern prototype racing, with the optimized tires providing seven percent more contact patch.

It came two years prior to LMP1 rivals Audi and Peugeot implementing the same strategy.

“The larger contact patch means more tire on the road and that certainly helps cornering and braking,” said then Michelin North America motorsport technical director Karl Koenigstein.

“You have a wider front tire to spread the load around which helps, but you are braking later and carrying more speed into the corner. 

“You are really working the front tires much harder than before.”

Patron Highcroft Racing and de Ferran Motorsports debuted the revolutionary Acuras in the Mobil 1 Twelve Hours of Sebring, with IndyCar ace Scott Dixon blitzing to the overall pole, ahead of diesel juggernauts Audi and Peugeot.

The Kiwi credited the car’s superior cornering speeds, courtesy of the wide front tires.

“It was definitely nail-biting,” Dixon said at the time. “On the first run you always try to put a time down and they came back and matched that.

“We tried to push as much as we could and luckily this car seems to get quicker and quicker on its tires.”

While both Acura LMP1 cars failed to finish in its debut race, the de Ferran and Highcroft teams went on to claim overall victories in eight of the remaining nine races that year, with Scott Sharp and David Brabham taking the title.

The innovative program, however, was brought to a halt at year’s end, due to lack of competition as well as the global financial crisis, which impacted Acura’s plans to take the car to the 24 Hours of Le Mans.

It also resulted in limited tire development to the “wide fronts” according to Koenigstein.

“The real pity is that the market crash in ’08 and subsequent lack of heavy factory competition meant that we didn’t go for a complete development of the concept with dedicated steer tires,” he said.

“If they had, Acura would have had a two-year head start on the concept vs. Audi, Peugeot and Toyota and it would have been very, very tough to for the competition to catch up.”

The concept was fully proven on the diesel-powered LMP1 cars in 2011, with Benoit Treluyer completing a quintuple stint on the same set of Michelin tires in his Audi R18 TDI en route to victory at the 24 Hours of Le Mans.

John Dagys is the founder and Editor-in-Chief of Sportscar365 as well as the recently launched e-racing365 Web site for electric racing. Dagys spent eight years as a motorsports correspondent for FOXSports.com/SPEED Channel, and contributes to other publications worldwide. Contact John

8 Comments

8 Comments

  1. JeffB

    November 25, 2017 at 11:17 pm

    Having the front tires be the same size as the rear tires may have led to an increase in performance, but, were a big part of the decline in aesthetics of the modern prototypes.

    The earlier increase in ride heights was part one, the larger fronts were part two and the removal of the louvers on the top of the fenders which led to the vertical, blunt nose front fenders to direct air around the wheels rather than the classic sloped nose cars that directed air over the wheels, was strike three.

    Many would say the large fins were the next step in the death of LMP aesthetics. Either way, I’ll take the elegance of a Porsche 962 over a homely Porsche 919 all day, any day.

    And don’t even get me started on the abomination of a 2016 Audi R-18 in comparison to a gorgeous 2000-2005 Audi R8…

    • Jonny Austin

      November 26, 2017 at 2:21 am

      The latest LMP1 cars are not pretty but I do think they look purposeful.Anyway the Porsche 917 & Ferarri P3 era had the nicest looking cars…

      • Limerockian

        November 26, 2017 at 6:58 pm

        The blunt nose design was because the large overhang nose led to the cars flipping over when air got underneath.

  2. Anonymous

    November 27, 2017 at 5:41 am

    The Acura ARX-02a without question my favourite LMP-1 of the last decade especially in the classy-looking De-Ferran livery, just a shame it never went to Le-Mans.

    • NASCAR/DPs Suck

      November 27, 2017 at 11:40 am

      That car never got the engine it needed and the necessary tire support but I was also a really big fan of it. The lap that Dixon put in to get pole that year was downright amazing.

  3. Jordan

    November 27, 2017 at 1:35 pm

    The 2009 12 Hours of Sebring was also the only race that both the factory Audi’s and Peugeot’s participated in where neither one would claim the pole.

    The Peugeot’s and Audi’s would end up yo-yo-ing each other for the lead for the entire race in which there were only 3 full course cautions.

  4. George 917-30

    November 28, 2017 at 10:45 am

    One of my favorite cars, enjoyed seeing and photographing them at Mosport and Petit that year. I distinctly remember walking the paddock during the race and being passed by Dixon’s mud-streaked Sirius car, after his big off in the rain (which shortened the race), and I have a photo of the car sitting alone, looking forlorn, when the race was finally called.

    Wasn’t part of the wide front tire advantage taken away by a rules change (said to be instigated by Audi and Peugeot) that reduced rear downforce, which unbalanced the car as designed by Wirth, requiring giving up front downforce?

  5. Gerald Wiley

    November 30, 2017 at 6:13 am

    There was a good reason the Audis and Peugeots weren’t on pole for that Sebring race – politics. As I understood it (from a VERY good source on the inside at the time) neither manufacturer wanted to be penalised for Le Mans against the petrol cars, so they had a gentleman’s agreement to run with something like 60 or 70% throttle in qualifying. In the race they ran at almost full pull, which explains why the fastest Peugeot was over 2 seconds faster in the race than qualifying (and the Audis were well over a second faster), yet the Acura was around 0.3s slower than its pole time.

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