In what was perhaps the most essential design revolution in the history of tires, Michelin introduced the radial tire in 1946. As compared to the old “bias” tire structure, radial tires offered benefits across the board, especially in the areas of tread life and (reduced) rolling resistance.
While it wasn’t known at the time, the radial tire invention would come to have long-lasting and profoundly positive effects on the environment. Since the late 1960s when the radial tire was fully adopted in the United States, tire engineers have been honing and improving the construction details. Today, some tires are delivering 100,000+ miles, which could never have been a reality without radial construction.
But despite radial tire technologies that have drastically improved tread life and longevity, the world’s driving population produces over one billion scrap tires every year. About 50% of those scrap tires are currently recycled.
Michelin is leading the way in terms of how best to recycle, reuse, and utilize all the elements of expired radial tires. The goal is to improve the recycling rate of tires from the current 50% to 75% over the next three decades.
So how are scrap tires recycled and reused?
Radial tire construction is far more complicated than the surface (tread) level details suggest. Just under the rubber compound exterior are numerous elements and materials; in fact, some 200 raw materials are included in a tire’s construction.
Elements of a tire include:
- Synthetic rubber on the inner liner (the most interior section of the tire)
- Textile fiber cords that are integrated into the rubber
- Extremely strong wire “beads” that seat the tire on the rim and ensure an airtight fitment
- “Belts” are steel cords that are bonded into the rubber
- Integrated nylon-based cords further strengthen the rubber and help keep it from deforming under extreme driving conditions
Once tires are recycled and deconstructed, the various tire elements have a wide variety of real-world uses and applications.
- Tire chips are used under roads in cold climates to limit frost penetration and better maintain pavement condition. They’re also a substitute for gravel.
- “Crumb rubber” is used for rubberized asphalt, floor mats, anti-fatigue workplace mats, and vehicle mudguards.
- Scrap tires are used as garden mulch that’s superior in many ways to standard wood mulch, asphalt roads, and construction materials.
- Clean fuel/energy is created through a high-temperature process called Pyrolisis.
The front end of Michelin’s tire construction process is also oriented with sustainability and environmentalism in mind. A remarkable 80% of new Michelin tires are constructed of recycled materials, including — you guessed it — expired tires.
The tire recovery/recycling process is ever-improving, and per Michelin, already more effective than the recycling process for the world’s overabundant plastics.
Along with the hybridization and electrification of the automobile, tire recycling advancements will help to ensure an increasingly limited automotive environmental impact in the coming decades.