Over 200 raw materials go into tire composition. Researchers draw on this extensive array to combine tire components, each of which has a role to play, depending on the type of tire produced. The rubber compounds are made up of elastomers, renforcing fillers, plasticizers and others chemicals elements.
Milky, white latex, containing rubber globules, is obtained by making an incision into the bark of rubber trees, the cultivation of which requires specific climatic conditions and rainfall. Rubber tree plantations are mainly located in Southeast Asia (including Thailand, the world’s largest producer and Indonesia), Latin America and Africa. In compound formulations, natural rubber reduces internal heat generation in tires, whilst offering high mechanical resistance. It is used in many parts of the tire, mainly used for truck and earthmover tire tread.
60% of rubber used in the tire industry is synthetic rubber, produced from petroleum-derived hydrocarbons, although natural rubber is still necessary for the remaining 40%.Synthetic elastomers deform under stress and return to their original shape when the stress is removed (hysteresis).This property is extremely valuable for the manufacture of high-grip tires. Synthetic rubber also provides other specific properties, most notably in the areas of longevity and rolling resistance. It’s mainly used for passenger car and motorcycle tire as it gives them good grip performances.
Discovered in 1915, carbon black added to the rubber compound produces a tenfold increase in wear resistance of the tires. It represents 25 to 30% of the rubber composition and gives tires their distinctive color. Indeed, this color is very effective in acting against ultraviolet rays to prevent the rubber from fissuring and cracking
Silica, obtained from sand, has properties that have long been recognized, including the improved resistance of rubber compounds to tearing. In 1992, Michelin took a major step forward by combining an original silica and a specific elastomer with a special bonding agent using a special “mixing” process. The compounds obtained make tires with a low rolling resistance, good grip on a cold surface and exceptional longevity. This innovation is at the origin of the green tires with low rolling resistance.
Sulphur: Sulphur is a vulcanizing agent that transforms the rubber from a plastic to an elastic state. Its action is accompanied by retarding and accelerating products used simultaneously during production which optimize the action of heat when the tire is cured.
The tire needs metal and textile reinforcements in addition to the rubber compounds. These are the real framework of the tire, ensuring its geometry and rigidity. They also provide the flexibility required for tire contact with the road.
Pioneers in drawing fine wire from hard steel, Michelin introduced steel into its tire reinforcements in 1934. This major technical advance, combined with the development of a coating providing a strong physical-chemical bond between the rubber and steel, was industrialized production in 1937 in the Michelin Metalic truck tire. Since then, steel has been adopted in the reinforcement of belts for radial tires. Metal reinforcements give the tire resistance and rigidity.
Textile has always been used to strengthen tires. In 2001, thanks among other things to an innovation in this field, Michelin tires enabled Concorde to take to the air once again. Fabric reinforcement currently plays an important role in high-performance, high-speed tires. Polyester, nylon, rayon and aramid are all used to manufacture the reinforcements, which provide added resistance, endurance and comfort.