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A tire is not just any round, black piece of rubber. In addition, the engineers at Clermont Ferrand like to remind that it is dark gray! But also that 200 ingredients are used to design a tire, grouped into large families: 10% metals, 24% natural rubbers, 25% synthetic rubbers, 7% textiles, 14% additives and 20% reinforcing fillers (mainly carbon black and silica). The properties of each ingredient can also be adjusted to get a tire that offers more or less grip, is more or less durable, consumes more or less energy or is even more or less aesthetic. Michelin develops tires for all types of vehicles, from 2 wheels to airplanes, the limitations and prejudices vary even more.
From these materials, the tire is developed on the basis of three main areas, which makes it possible to achieve a high-performance tire: firstly, the construction, involving the fabrics and metals. Then the geometry, which relates to the profile of the tire and the design of the tread. And then the chemical composition, especially on the tread, which determines the level of grip and endurance. For this last point, elastomers play a major role, as they only represent half of a tire’s composition. Everything starts with butadiene and styrene, monomer-type molecules that, when reacted together, can form a polymer of the elastomer family. We’re not going any further in chemistry class, don’t worry.
The importance of an elastomer, as the name suggests, is its elasticity. The chemist can then make it more or less extensible, with a rather slippery or rather rough contact feel to schematize. Properties that tend towards low rolling resistance or the opposite of ground grip. Let’s take a concrete example with two small balls with different elastomer compositions. One bounces very little, meaning a lot of energy was dissipated in the ground at the point of bounce. For a tyre, this property works in favor of grip. Conversely, the other ball bounces a lot, with the ability to hold energy with it. An ideal property for, for example, a bicycle tire, which requires little grip and rolling resistance, thus wasting as little energy as possible, which is delivered courageously by the strength of the legs.
Another example, by drawing two samples of elastomers with opposite properties. The first is rough but yields easily, showing good grip but low staying power. The other sample is stretchable almost infinitely, a testament to good longevity, but feels soft and therefore much less adherent. Extreme examples here, of course.
The choices for a car or bicycle tire
Illustrative photoCredit photo – Michelin
By adapting the properties of these elastomers and other tire ingredients, it is therefore possible to tailor a product depending on what it is being mounted on. And thus comply with very precise specifications: a sports car tire, such as the Pilot Sport 5, must therefore be able to bear a load of 500 kg (which, multiplied by four tires, corresponds to the total weight of most sports cars , with the exception of large sedans or SUVs). It must be able to give its full potential at an average pressure of 2.3 bar and must be able to withstand speeds of 50 to 300 km/h (or even slightly more). All with very low camber (or lean, shall we say), on the order of 1 or 2 degrees. The contact area of a car tire with the ground is also widest in front of the 2 wheels. For example, the Road 6 motorcycle does not have to carry more than 120 to 175 Kg, between 2 and 2.9 bar, but also from 50 to 300 km/h. The camber is crucial this time with angles that can reach 55°. Finally, a bicycle tire is even more special. For example, the new evolution of the Power Cup has a load carrying capacity of only 50 kg, at a high pressure of 8 to 10 bar, for an average speed of 30 to 90 km/h. The maximum camber to collect is lower, on the order of 30°, all due to a ground contact area that is kept to a minimum here.
Michelin will then take certain biases to make it more efficient with these limitations, by playing on grip, rolling resistance, wear and stiffness. For example, this last point has been increased on the PS5 in particular to provide better directional power, an asset when playing in the laces.
A Road 6 doesn’t need that much stiffness on the center tread. By crushing light in a certain way, the idea is to increase the contact area, to provide more efficiency in braking or traction. At the edges, the stiffness decreases further to increase the contact area in bends again and again. In combination with a soft chemical composition, this increases the adhesion, also in the name of safety, which is a high priority for corner handles. On the other hand, the rolling resistance decreases and the wear on the edges is slightly more important than in the middle. A sacrifice also necessary to maintain a rounded tire profile as it wears and to prevent it from becoming “square” if the central tire wore out faster than at the edges.
For bicycle tires it is a different story. The cyclist, on the other hand, needs the lowest possible rolling resistance so as not to waste the efforts of the thighs. On the Power Cup it is much lower than with car or motorcycle tires. Conversely, the grip level is also much lower. Imagine if the cyclist bites too hard on the asphalt when braking, that is guaranteed “sun”. At the corner of the tire, the grip doesn’t have to be very high either because with 30° maximum cornering angle, in reality the cyclist doesn’t exert that much stress with the risk of picking up. It is easy to see during a stage of the Tour de France, cyclists work out their trajectory to take the smallest possible angle and maintain maximum speed. Either way, if it took too much of an angle, the pedals would be a problem. On the other hand, stiffness is important on a bicycle tire, which is by definition very thin. The cyclist must feel that he can lean firmly on his tire and above all not feel a certain softness, such as a tire that is somehow underinflated. The wear of a Power Cup is also very low because it should last as long as possible despite the thin rubber. An easier feature to set up when grip is not essential.
The properties of a tire all have a certain logic, in short: it is a matter of lowering one slider to increase the other.
Pilot Sport 5: Outperform the critically acclaimed PS4
Illustrative photoCredit photo – Michelin
Nevertheless, Michelin aims to raise the bar in all areas with the Pilot Sport. For the 5th generation, the Bibendum should do even better than the multi-award-winning PS4. So the manufacturer has slightly increased the sliders for driving pleasure and longevity, while adopting the new eco-design methods that are dear to the brand today. Keep in mind that if the Pilot Sport Cup R is the ultimate tire within Michelin’s sports range for track days, for example (before switching to semi-slicks or slicks), the Pilot Sport 5 is intended for normal everyday use, while by offering the option of occasional random fun on a winding road.
The improved performance is, of course, the result of lengthy research into materials, design and construction, materialized by numerous patented technologies. Glossary: Dynamic Response Technology uses a hybrid nylon and aramid belt to increase stiffness when loading the tire, improving responsiveness, as seen above. The Maxtouch construction increases surface contact with the ground, so that the grip or drainage of water is more homogeneous across the width of the tread. The Dual Sport Tread Design refers to the asymmetrical tread structure and offers both wet (outside the tread) and dry (center and inside) qualities. The Groove Clear technology corresponds to these 4 wide grooves that allow maximum water drainage, the first defense against aquaplaning. Even if all manufacturers have their own proprietary inventions, the last two technologies mentioned above contribute a lot to the Pilot Sport’s reputation for its wet performance.
There’s one last rather surprising axis of development on today’s tires and particularly evident on the PS5: aesthetics. From now on, the engineers responsible for tire design work together with the design teams. The challenge of this partnership is to maintain all the qualities that make the reputation of this sporty range of Michelin tires, while generating a sense of achievement just by looking at them. The design of the structures has been worked in this direction, in flashes on the PS5, a sign of “lightning” efficiency. It has hardly been extrapolated because the shapes of this flash of light or, in another style, the bent position of a fencer, were real sources of inspiration here. The sidewall of the tire is even more telling: Michelin was this time inspired by the fur of the fast black panther, materialized here by a feeling of velvet to the touch and an identity mark that is clear. A few other additional details, such as checkered patterns, clear up any ambiguity about the PS5’s sporting intentions.
Future Development Levers
Illustrative photoCredit photo – Michelin
Michelin has already given us an idea of the tire of the future with its Tweel technology, which requires no air pressure. However, it is not for now as far as high-performance tires are concerned. éIn the short term, the French manufacturer, like the others, is mainly working on ecodesign. By producing tires that are lighter, even more durable and less and less resistant to roll. In addition, Michelin now offers a Pilot Sport EV for electric vehicles that must take these parameters all the more into account in order to comply with the idea of a clean vehicle. Reducing emissions from the delivery of tires to distribution points is a hot topic. Also, produce locally, with closer subcontractors. The use of sustainable materials is also part of today’s specifications, with Michelin aiming for 40% sustainable materials in a tire by 2030 and 100% by 2050.