If you watched the IndyCar race in Nashville last weekend, you might have noticed some tires with green sidewalls that adorn some of the cars. Bridgestone’s new tires, made in part with rubber harvested from the guayule shrub, make sports car racing debut. The company says the new ingredient helps propel them towards their goal of completely renewable and carbon-neutral tires.
Named Firestone Firehawks, they were used as replacement tires for Big Machine Music City grand opening. The branding of Bridgestone’s U.S. subsidiary is important, as the guayule is native to the Southwestern United States and Mexico, and part of its enduring appeal lies in the fact that the guayule is local side to the market. Tires are manufactured at Bridgestone’s Akron, Ohio plant.
Guayule shrubs thrive in hot, arid climates and don’t require much water to grow, a boon for these arid regions. In addition, the guayule tree needs less time to grow before it can be harvested, just three years compared to the five years required for the para tree, the main source of rubber today. Best of all, the guayule does not compete with food crops, nor does it require additional equipment to grow; it can be harvested using existing conventional planting machinery.
According to Bridgestone, the rubber from the guayule tree is very similar in composition to the rubber from the para tree. Currently, tell IndyCar, a rubber derived from guayule is used in the sidewall construction, the area of the tire with the most natural rubber. Bridgestone is using the racing season to test its effectiveness and hopes to find ways to incorporate it into its racing tires by 2023.
On the other hand, the production of guayule rubber is more complicated. It requires solvent treatment to separate the rubber from the rest of the plant and clean the material. It has been 10 years since Bridgestone began researching guayule as an alternative rubber source. It maintains a 287-acre guayule farm at its research facility in Eloy, Arizona. The company has invested $100 million so far in this research, and hopes to be carbon neutral and have a tire made entirely of renewable materials by 2050.
