A new age for tires
Continental, Goodyear and Michelin disclose their vision of the future by focusing on innovative and sustainable components
What will tires be like in the future? Three global manufacturers share their view.
There is no doubt that the automotive industry is undergoing a momentous transformation. The whole sector is called upon to deal with new models of mobility, changes in people's habits, a growing number of car-sharing operators as well as the spread of new vehicles, such as EVs, both for freight and people. In addition to these trends, there are complex environmental, legislative and regulatory issues that interact with each other and with industrial policies. As expected, tires as a crucial element even in modern vehicles, were not spared the effects of this wave of new developments. What better way to obtain information on these developments than to ask those who are playing an active role in this transformation? So we got some insider information from 3 well-known global manufacturers.
Continental needs no introduction: we are talking of a long-standing tire manufacturers, with 150 years of experience. Today, Continental is not only the world's fourth largest tire manufacturer, but also a giant in the field of "traditional" and high-tech components such as sensors, cameras, radars and thousands of other parts for suspension, powertrains and so on. As far as the evolution of compounds there is little doubt that the use of nanomaterials have accelerated the process. Research on compounds had trailed plies and belts for a considerable time, but things have changed. Silica, introduced around 1995, played a crucial role in improving performance and grip both in dry and wet conditions. Nanoclays are also the subject of intense studies, aimed at simultaneously improving three seemingly conflicting areas: rolling friction, grip and resistance to wear and abrasion. Improving this last aspect not only increases the useful life of tires but goes a long way in reducing emission of particulate matter.
Fillers and frequencies
The Black Chili compound used in ContiSportContact 5 uses 1 micron carbon black and high dispersion silica to optimize the reaction of both long and short polymer chains. Hence, the longer chains, with a frequency similar to what is found in tires, avoid dissipating too much energy and reduce rolling friction. Frequencies go up during braking or acceleration and here the shortest polymer chains kick in: this increases the transfer of energy to the ground, which is essential when accelerating. The main characteristics - rolling friction, grip and wear resistance - are only a part of what a tire is called upon to deliver: all together they are in fact 54. Safety, for example, includes sub-parameters starting from longitudinal and transversal aquaplaning and so on. Continental’s Sport 6, available also for 22-inch wheels, boasts an even more advanced compound with high dispersion silica: the tires perfectly adapts to the roughness of the road surface improving grip even if fuel consumption is affected a bit. Fabrics are also evolving: ultra-high performance tires put a lot of strain on the plies, which are entrusted to maintain the tire’s profile even against high centrifugal forces. In this case, Continental uses aralon, a fibre made up of interwoven aramid and nylon fibres: varying the proportion of the 2 materials you will have a yarn that combines the tensile strength of the aramid with the elasticity of nylon. This synthesis is necessary: a tire with aramid-only belts would be non-deformable, too rigid, while nylon alone would be too flexible. In Conti Sport 6, the amount of aralon changes when the size of the tire changes.
The EU Reach standard (the European Regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals) has forced the industry to invest heavily in replacing the previously used aromatic hydrocarbons. Regarding the proportions between artificial and natural polymers, we have learned of an increase in the amount of synthetic polymers at the expense of natural rubber. The availability of the latter, in fact, is limited and used by other sectors as well. Continental is experimenting with the use of dandelion, not exactly a new idea, but one that requires major changes: a rubber tree gives 2 litres of latex, a dandelion plant a few drops. This translates in an increase in the workforce needed to grow the plant and the areas to be cultivated, besides, dandelion is more adaptable and lives in climates that are prohibitive for the rubber tree: making it possible to grow the dandelion near in the proximity of factories at a faster rate, being a plant and not a tree. Talking about “smart” tires, we should mention ContiSense and ContiAdapt prototypes. The ContiSense's electro-conductive compound makes it possible to detect the deformation of the tread and communicate with sensors located throughout the tire. Obviously, this system must be assisted by a sophisticated software that "cleans" the data and interacts with the on-board systems. An area in which Continental has been investing significant amounts of cash for some time, thanks to its expertise in the field of sensors and processing of signals.
Smart wheels and tires
The ContiAdapt system provides for a wheel whose variable diameter capability is managed by micro-compressors. The footprint of the tire on the ground and its stiffness can, therefore, be modified: working with vehicle manufacturers, several points are defined according to the expected working conditions, in order to optimise the tire’s performance in every situation. This requires greater communication with the vehicle, given that, to date, the digital development of tires is still lagging a little behind, but the fact remains that tires are the only contact between the vehicle and the road. As far as EVs, we were told that the first electric cars, having low capacity batteries, needed minimum friction and for this reason narrow tires and large diameter wheels were the favourite choice. Nowadays, though, electric vehicles are equipped with “normal” tires: Tesla’s Model S, being a high-performance car boasts a set of Sportcontact 5. The development work on tires dedicated to electric cars does not differ from that of conventional vehicles: work start with a “Requirement Book” in which car makers describe the technical features of the vehicle’s components, including tires. On the basis of this, prototypes are developed and from these the one best suited to the vehicle’s requirements is chosen. This can also lead to exclusive markings such as the BMW "star" or the acronyms MO from Mercedes and TO, Tesla Original and so on, but this is true for all models, not just EVs. In general, electric cars need low-resistance tires, without compromising on essential qualities such as safety and grip. Full-electric cars, traditionally have a low centre of gravity, which is an advantage as it reduces rolling. Regenerative braking guarantee a longer life to the brakes but, even if it were to occur only at the rear wheels, it would still not be appropriate to mount different tires just for this reason, as this would mean losing the opportunity to rotate the tires thus increasing their lifespan.
Currently, the possibility of printing the tread in 3D is a topic of major discussions in the field of tire production, as this would mean changing the tread according to requirements or regenerate it when worn out. However, on this hypothesis, Continental, while respecting the choices made by others who are looking at similar solutions and considering them interesting for the environment, prefers to go about it with great caution. The curing process would prove a technological obstacle: how can you cure a "printed" tread? Furthermore, how would it fit on the casing and how would it integrate with the bead, and so on: to date, technology, in this respect, is still quite limited. Another line of research is that of airless tires: Continental keeps considering them, also because they are “immune” from punctures; however, their development, at this stage, is not a priority and will only take place if there is a real demand. Meanwhile, Continental has observed that all-season tires have experienced a huge initial growth only to reach a plateau. Continental considers them suitable mainly for small and medium sized cars used on a limited mileage in mild climate conditions. It should be remembered that all-seasons are still waiting for a definitive regulation, but if winters should become somewhat milder in the future, their demand might soar. On the other hand, in hot or cold weather conditions the best solution is a classic "double set".
Goodyear is dead set on developing new components, as a company that has always been committed to working on technological innovations. One of the most recent is the use of silica from rice husk ash or soybean oil. Goodyear has developed an innovative industrialization process of soybean oil, an example of research and development on sustainable materials that can be beneficial not only to the environment but also to tire performance, as these mix well with silica, reduce energy consumption and increase the useful life of a tire reducing Goodyear's dependence on oil.
Electric vehicles, with their high torque and the need to minimise rolling resistance, have a certain influence on tire compounds, structures and treads. That is why Goodyear works closely with car manufacturers on resistance, as these cars are heavier due to the presence of heavy battery packs and their electric motors transfer high levels of torque to the wheels. Tests have shown that tires can wear out 10-30% faster compared to tires found on traditional ICE vehicles. Goodyear engineers are working on rolling resistance to maximize the mileage potential of electric vehicles. At the same time, work is being carried out on reducing rolling noise, because quiet electric powertrains do not shield the roar of internal combustion engines. Studies are looking at combining this characteristic with significant improvements in handling and grip. As far as producing treads in real time with 3D printers, Goodyear thinks it is too early to have a clear opinion on the matter. True, Goodyear unveiled its Oxygene concept in 2018 at the Geneva International Motor Show as a 3D-printed tread, but that was a purely conceptual development and therefore too early to predict any immediate developments. However, we would like to recall that the Oxigene, besides containing CO2 absorbing moss able to release oxygen, boasts also a light emitter designed to exchange data with infrastructure and other vehicles.
Sustainability is a key topic in Michelin's vision, as important as tire connectivity. By 2048, Michelin will be producing tires made from 80% sustainable materials with a programme that will bring the proportion of recycled tires to nothing short than 100%. This is a big step forward, as currently 70% of used tires are recycled: 50% recycled as second hand materials and 20% used to produce energy. Today, Michelin tires contain 28% sustainable materials, 26% natural materials such as rubber, sunflower oil, limonene and the like, while the remaining 2% - steel and rubber powder - comes from recovered and pulverised tires.
We recycle and plant trees
Michelin's commitment to sustainability is well known. An example of this is the Biobutterfly programme launched in 2012 with Axens and IFP Energies Nouvelles to produce synthetic elastomers from biomass such as wood, straw or beet. This also includes an agreement with Amyris to develop and market isoprene derived from biomass. This partnership was then extended to include Brazilian Braskem, the world's largest producer of biopolymers: its products are used to supplement natural rubber, which is also the subject of international agreements. Remember that natural rubber is an irreplaceable raw material in the production of tires for trucks, earthmoving machines and aircrafts. Michelin's interest in this sector has resulted in an alliance with Barito Pacific Group to reforest three areas in Sumatra and Borneo. An area of 88,000 hectares, devastated by uncontrolled deforestation, that will be reforested with rubber trees for about half while the other half will receive plants for the local community as well as endemic plant species. This will result in 16,000 local jobs and a production of 80,000 tons of natural rubber, or about 10% of Michelin's needs, which will should also limit the volatility of raw material prices. Currently, Michelin makes extensive use of eco-sustainable materials, such as natural rubber and vegetable oils. Looking ahead to 2048, the French brand is developing ground-breaking solutions to increase recycled and renewable materials. This is the background to the recent acquisition of Lehigh by Michelin, a company specialising in high-tech micro-dusts produced from end-of-life tires. Lehigh is the market leader for Micronized Rubber Powders (MRPs), sustainable powders that reduce raw material costs by up to 50% while achieving uncompromising performance in a wide range of applications such as high performance tires, plastics, consumer goods, coatings, sealants, construction materials and asphalt.
Hackathon challenges and lessons from nature
The French group is also promoting its ideas through hackathons: the one organized in 2017, in partnership with Alliapur, saw the victory of "Black Pillow", street furniture created from rubber granules. And the most recent Live the Motion, involved students from the Polytechnics of Turin and Milan as well as the University of Palermo, who challenged each other with innovative projects for safe and sustainable mobility. Innovation also concerns industrial processes: an agreement with Fives, signed in April 2016, created Fives Michelin Additive Solutions. This joint venture creates sophisticated tire moulds thanks to an AddUp solution such as FormUp 350: a ground-breaking and flexible machine that produces prototypes by melting layers of metal powder with the laser. Michelin’s Vision concept, a 100% recyclable airless system made of materials from sustainable sources, is a clear demonstration of the French manufacturer’s innovative drive. Besides being sustainable, Vision is also connected and thanks to an app it will be possible to change its tread thanks to 3D printers. Its structure is solid at the centre, as it encloses the wheel, but flexible at the side and at the footprint; based on an alveolar structure that mimics natural structures, Vision is made come from wood chips, straw, sugar, sugar residues and orange peel, while the natural rubber used comes only from environmentally friendly plantations.
Vision’s connectivity is already available, at least in part, in racing tires. Michelin Track Connect tires have been available since last April. This Michelin-connected solution uses technologies already in use in industrial vehicles and aircraft and makes them available to private individuals. The umpteenth app suggests the suitable tire pressure and the conditions of the race. During the competition Track Connect gives the driver real-time information on the pressure and temperature of each tire; any changes in pressure is detected as well as any issue with over-steering and/or under-steering. After the race or test sessions, the app indicates any pressure corrections to be made before returning to the track: Track Connect can also detect whether the tires are working according to the chosen setting, i.e. dry, damp or full wet track. The system possesses information on various circuits and stores lap times for a quick comparison on the effects of the changes made.