What Are IndyCar Tires Made Of?
On August 4, 2022, Bridgestone Americas, owner of Firestone Tires, announced that official IndyCar tires will be made from guayule, a plant native to the deserts of the state of Texas, in the United States, and the Mexican states of Chihuahua, Zacatecas, Nuevo Leon and San Luis Potosi.
Complying with part of its goal to use sustainable technologies in the NTT IndyCar Series, the tire developed for racing features a sidewall made with natural rubber from a bush named guayule. So we came here to explain more about guayule tires and their production.
IndyCar & Bridgestone
The IndyCar Series, currently known as the NTT IndyCar Series, is the championship that runs the Indianapolis 500, one of the most prestigious races among all motorsport series, while Bridgestone Americas, Inc. is the North American subsidiary of Bridgestone Corporation, a tire and rubber manufacturer based in Nashville, Tennessee. In the late 1980s, Bridgestone and the tire company, Firestone, merged, and today Firestone is the exclusive supplier of tires for IndyCar racing.
Bridgestone's commitment to sustainability
The Bridgestone Group created the "Bridgestone E8 Commitment," which consists of 8 fundamental values that serve as guidelines to promote sustainability within the company and commitment to the world. Its values are energy, ecology, efficiency, extension, economy, emotion, ease and empowerment.
In addition to E8, Bridgestone is committed to reducing CO2 emissions, actively researching solutions to support the recycling of tire materials, and promoting the replacement of non-renewable materials such as oil, silica, and virgin carbon black in new tires. The Firestone Firehawk racing tire initiative with guayule aligns with the company's "Emotion," "Ecology," and "Energy" commitments and is part of Bridgestone's plan to achieve carbon neutrality and manufacture tires with 100% renewable materials until 2050.
How is guayule used in the tires?
Natural guayule rubber is located inside the sidewall of the Firestone Firehawk. Bridgestone's racing tire engineers used guayule rubber throughout the sidewall because this area comprises the most natural rubber. This allows Firestone to maintain the same quality and performance as the existing race tire.
Guayule tires are the result of more than a decade of research by Bridgestone, with the project starting in 2012 at the same time that a research and development center opened in Arizona. So the guayule is grown on a 287-acre farm and processed in the center's facilities. After that, the race tire production plant in Akron, Ohio, transforms it into the alternative Firestone Firehawk race tires. The first tire containing natural rubber derived from guayule was produced in 2015, and to date, Bridgestone has invested more than US$100 million to market rubber from the plant.
When were the tires introduced in IndyCar?
Race tires with sidewalls made from guayule were first introduced at the Indy 500 Pit Stop Challenge (Indianapolis 500) in May 2022 as a first attempt before it debuted in competition as an alternative race tire at the Big Machine Music City Grand Prix in August 2022.
"The introduction of guayule natural rubber to America's pre-eminent open-wheel racing series speaks to the confidence we have in the technology and its promise as a scalable, sustainable and domestic source of natural rubber—a vital raw material," said Nizar Trigui, Chief Technology Officer and Group President, Solutions Businesses, Bridgestone Americas, Inc. "This milestone represents our commitment to realizing a more sustainable future for tires, racing and mobility."
For the 2023 season, guayule-based tires will be used at all street circuits and Bridgestone intends to commercialize guayule rubber by 2030 and will continue to improve guayule productivity through sustainable methods.
Throughout history, guayule emerged as a domestic source of natural rubber and economic promise for the American Southwest. It is a shrub native to the arid zone of the southwest of the USA to the north of Mexico and, therefore, can be grown in environments totally different from those suitable for rubber trees (Brazilian tree and primary current source of natural rubber) and, in addition, the constituent of rubber contained in it is very similar to that of rubber trees.
The process for producing rubber from guayule is more complex than that from rubber trees, but faster. The plant takes about 3 years to get the right size for processing. After that, it is harvested and taken to a grinding process. Afterwards, the rubber will be extracted from a solvent and the next step of the process is removing impurities from that rubber and removing the solvent present in it. It is worth noting that natural rubber can be extracted from the bush's branches, bark, and roots.
On the other hand, extracting natural rubber from a rubber tree can take much longer, as it takes about 20 years for a rubber tree to grow and reach the adequate size for latex extraction. After that, the latex removed is left in a coagulation and drying process until natural rubber from the rubber tree is obtained.
It is worth noting that guayule is currently not a commercial crop, so Bridgestone must produce the seed and cultivate the harvest. In addition, the bush does not compete with traditional food source crops.