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4T : Fourtitude Features Reviews & Road Tests

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23 December 2016


Michelin Brings Racing Engineering and Experience to the Road

One of my biggest passions in life is Motorsports. I love watching car racing both in person and on TV, especially when any Audi Sport teams are racing. For myself, one of the most interesting aspects of racing is the strategy. The team’s approach is often more important than the driving itself. There are many factors the race engineer must consider, but some are more crucial: weather, fuel, driver, and tires. Just like in racing, putting the right tires on your car is incredibly important.

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My 2016 Audi S6 arrived from the factory with the 20-inch 5-double-spoke Titanium matte wheels wrapped in Pirelli P-Zero 255/35 summer tires. The P-Zeros were the OEM tire on my previous 2014 SQ5 and 2010 S4, and I thought they were loud, quick to wear, have a delayed response to steering inputs as the uniformity of the tire is not great, and the wet traction is just okay. I had quickly replaced them on both vehicles. I put about 2,000 miles on the P-Zeros on the S6 to get a baseline for myself of their performance and wear. I like to enjoy my cars, and I love to push them hard. It’s easy to learn where their limit is and not to exceed it. A proper set of tires will help increase the limit of the car and the enjoyment.

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Michelin offered me a set of Pilot Super Sports to replace the P-Zero, which allowed me to make a back-to-back comparison of the two, and after a month on my S6, I came to appreciate all they had to offer in both performance and comfort capacity. But first, a little background.

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The Pilot Super Sport Credentials

To better understand what goes into building the Michelin Pilot Super Sports, I spoke to Steve Calder from Michelin High-Performance Product Marketing and learned more about how Michelin has transferred their very same strategy and engineering used on the track to the road.

“When we say that the Pilot Super Sport was ‘born from endurance racing’ we are referring to our track to street philosophy of moving technology tested in endurance racing to street tires.” Steve went on to explain that during the development of the Pilot Super Sport, the finite element analysis (FEA) software that their designers used to design and model the street tire were first developed and refined by the competition group. In other words, Michelin used the same software and “Variable Contact Patch” design philosophy to develop the PSS as they use to develop endurance racing tires.

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Also, the robust outside shoulder rubber compound is lifted almost directly from endurance racing tires. Michelin mixes the rubber with the same group in France that mixes the competition rubber. Michelin then flies the mixture to Greenville, South Carolina where Michelin consturcts the Pilot Super Sport tires.

Tires are one of the most direct links that bridge the gap between road cars and race cars. Tires are the point of contact with the road or race track under any but the most unusual circumstances. Michelin has spent an unfathomable amount of engineering time to make sure that the optimal amount of tire is contacting the road surface. This part of the tire is called the contact patch. The contact patch is often a tiny a percent of the overall tread surface. To help visualize the size of the contact patch you can place your hand flat across the center of the tread of the tire. The contact patch also varies with the scale of the tire and is critical to maximizing straight line stability, acceleration, braking, and cornering traction.

Many factors contribute to putting as much rubber on the road as possible. The first is the rigidity of the tire. If the structure of the tire is weak, to begin with, then you have already significantly reduced your contact patch. When you apply pressure to the top of some low-grade tires, you can almost push the top and bottom together. A stable tire structure also helps to control the centrifugal growth that occurs as speed increases.

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Michelin developed a high-density Twaron (aramid fiber). The Twaron is used to create a belt on top of the steel belts that controls centrifugal growth at high speed and to fine-tune the stress distribution in the tire contact patch. As the tires spin faster, they will change shape, often becoming skinnier, which reduces the contact patch on the road. Michelin engineers figured out a way to minimize the growth of the tire to maintain the contact patch and grip.

When deciding what types of compounds go into the tire and where they will be distributed, Steve explains that “the determination of the rubber compounds and the distribution across the tire starts with material property estimates from the rubber compounders and computer modeling. But the computer simulations and estimates can only take the process so far.” Steve went on to explain that a considerable amount of the development involves building prototypes and testing. It is not uncommon to build and test 20 or more variations during the development process.

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Lastly, I asked Steve to share something about these tires that the average person will probably not know. “Something most people do not know is that a ‘normal’ tire has upwards of 12 or more splices inside the tire where different materials, such as the tread rubber and steel belts, are put together.”  An improperly built splice can lead to performance problems, such as poor uniformity, noise, or even tire failure. “The process Michelin uses to construct the PSS is proprietary to Michelin and does not have a single splice anywhere in the tire.”

On-Road Performance

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Almost immediately, I found myself pushing the S6 further, even in places where I knew certain sections of the pavement would often cause the P-Zero to stutter – especially in tight turns. Passing over those same sections with the Michelin Pilot Super Sport resulted in a smoother transition. Braking also felt more confident as the same level of uniformity that helps maintain traction also helps to stop quicker.

Johnny Valencia, Michelin Community and Influencer Manager, went on to explain that this is due to the overall construction of the PSS. The fewer splices that you have in a tire, the better uniformity it will have. Uniformity is all about maintaining the overall shape of the tire. You can maintain better traction on uneven surfaces if the tire can retain its shape as you pass over rough, uneven surfaces or need to brake hard.

The S6’s cabin on the highway is an incredibly quiet place. Except for the occasional wind noise, the road noise from the tires is constant. The P-Zeros produce a moderate growl, while the PSS sound is more modest but still perceptible. Even with the focus of the PSS being about at-the-limit handling, it’s very easy to live with every day.

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I felt the wet weather handling characteristics of the P-Zero kept the S6’s Quattro system busy. In particular, when traveling through standing water I would often feel a pull in the steering wheel. There is still some feeling of pull with the PSS, but significantly reduced. Overall I feel like Michelin has delivered an incredibly well-balanced tire that can help any performance-car owner push their car a little closer to limit.

While the Michelin Pilot Super Sport tires may not be the answer to everyone’s needs, I feel that it’s important to have capable and safe tires installed on your car at all times. After spending the day talking to the staff at Michelin I realized that there is so little in contact with the pavement that it’s important to maximize that for your safety plus the safety of the others around you. The difference between swerving and losing control or being able to maintain control of your car ultimately rests on the tire choices that you make. A budget tire with weak construction will often lose much of its shape, especially under hard breaking, and will curl around the rim. It might be impossible to regain control, and that will make a bad situation even worse.

After a month on the Pilot Super Sports, I can say with conviction that there’s good reason they always come out on top in all the major comparison tests.

this review first appeared on quattroworld.com


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