Racing Toward Sustainability
The IndyCar Series is betting on a desert shrub to reduce its environmental impact
By Monique Davis, Cam Kauffman and Tracy Mejia
Felix Rosenqvist remembers the nerves he felt the time he flipped on the engine of his $650,000 Chevrolet race car during a practice ahead of the 2022 Big Machine Music City Grand Prix in Nashville, Tennessee. The IndyCar driver shifted into gear and tore down the straightaway. Although he had been racing IndyCars since 2019, there was something distinctly different about this race.
Rosenqvist, as well as the other 25 drivers who competed during that sweltering 90-degree August weekend, was using new tires made out of a more natural rubber that had never been used in racing before.
As he rounded curves and completed a few laps at speeds approaching 240 mph, Rosenqvist noticed that the new tires “fell off” quickly, meaning that they wore down and degraded much faster than their less sustainable counterparts. This, he said, made him skeptical that the tires would be durable enough to last an entire stint when it came time to race.
“By being more sustainable, we assumed that it was going to be worse.”
— Felix Rosenqvist
“We were all worried that they were going to last like five laps because it was a new product,” Rosenqvist says. “By being more sustainable, we assumed that it was going to be worse, just from an engineering standpoint.”
However, when the tires lasted for a whole stint, Rosenqvist said he and the other drivers were surprised that the sustainable wheels endured the harsh racing conditions.
“We were all like, ‘oh, shit, they’re actually really good,’ and that’s kind of been the case since then,” Rosenqvist says.
The new, more sustainable tires that Rosenqvist raced with in 2022 (Photo courtesy of Travis Hinkle)
Pressured by the constant threat of climate change, a deteriorating fan base and a society where environmentalism is at the forefront of people’s minds, the NTT IndyCar Series is pivoting toward sustainability.
IndyCar and Indianapolis Motor Speedway Senior Communications Manager Lauren Guidotti says the series’ push toward sustainability, beyond being for the sake of the environment, has reengaged past fans and piqued environmentally conscious people’s interests.
“It gives us this opportunity for people who maybe had never paid attention to motor sports before to say, ‘Oh, this is kind of interesting. I want to pay attention to this because I care about environmental issues,’” Guidotti says. “I do think it is absolutely helping.”
Because IndyCar is a sport that relies on speed, consistency and durability, any internal or external modifications made to the vehicle must take these factors into consideration to maintain the performance level both drivers and fans expect.
When it comes to the new tires, Rosenqvist said they have been “as good or better” than those prior, even if he was skeptical the first time he practiced with them.
“In a weird way, we haven’t really thought about it,” Rosenqvist says. “We just kind of called them the greens instead of the reds and moved on racing as we used to do.”
The “greens” Rosenqvist is referring to are the green-sided tires made by Firestone Racing, a subsidiary of Bridgestone Americas, that IndyCar drivers are required to use for at least one stint at each of the five street circuits on the 2023 schedule. The greens are meant to replace the “reds,” which are less sustainable and are now used solely at the remaining 12 road and oval courses.
What makes these green tires unique is that their sidewalls are made out of natural rubber extracted from a plant called guayule, a woody shrub that grows in desert climates and requires about half as much water as corn and alfalfa need to survive.
The way farmers harvest guayule also makes it stand out.
“They only have to take the top portion of it,” says Guidotti, who visited Bridgestone’s guayule farm in Eloy, Arizona. “The root base and everything stays in the ground.”
Leaving the roots in the ground also allows the plant to grow back on its own without needing to sow new seeds every time.
In additon, guayule's natrual latex is also being used to create bio-friendly fuel and medical devices like rubber gloves.
Previously, Bridgestone sourced all of its natural rubber from the sap of the hevea plant, which grows on Bridgestone-owned plantations in Indonesia. Getting the material from there to Akron, Ohio, where IndyCar tires are produced, took a long time and contributed to a hefty carbon footprint because the sap had to be transported by plane or boat more than 9,300 miles.
“There’s a lot of reliance on this one single source of natural rubber (hevea),” Executive Director of Race Tire Engineering and Manufacturing at Bridgestone Americas Cara Krstolic says, which prompted the company to look into guayule as another viable option.
Now, with guayule being grown domestically, Bridgestone is cutting down the distance some of its natural rubber material travels to less than 2,000 miles.
However, USC associate professor of civil and environmental engineering Ketan Savla says the automobile racing industry is so minuscule – some 35 cars comprise the IndyCar fleet – compared to passenger vehicle usage in the U.S. that the decrease in emissions caused by growing and transporting guayule domestically “will be a small drop in the ocean for the entire transportation sector.”
In fact, in 2021, the U.S. Environmental Protection Agency calculated that transportation made up the largest portion of greenhouse gas emissions in the country (28% of total emissions).
Tony Dutzik, associate director and senior policy analyst at Frontier Group, a non-profit research and policy organization whose mission is to build a healthier, more sustainable America, on the other hand, says he thinks that there is a bigger threat within the IndyCar Series beyond the emissions caused by transporting natural rubber: transporting fans to each race.
This year’s Indy 500 welcomed more than 330,000 fans, many of whom traveled from all over the country to attend the most famous race in sports.
“The vast majority of the environmental impacts from IndyCar are going to be from the facility itself and the transportation of people to the race,” Dutzik says. “The CO2 emissions that are produced in the process of staging the event are likely to be way, way higher than the emissions that are actually produced on the racetrack.”
Despite Savla’s and Dutzik’s concerns, the tire giant has not fully cut ties with its hevea suppliers just yet, and Krstolic says the company does not plan to for the time being.
“Having a diversity of natural rubber helps us as a business,” Krstolic says. “If something were to happen to that plant, then we have a backup.”
Although guayule is a 1-to-1 replacement for hevea, Bridgestone continues to import much of its natural rubber from overseas. The company announced last August that it will allocate nearly $26 million by 2030 to enhance the Indonesian plantations.
Bridgestone made approximately 30,000 race tires this year – 5,000 of which contain guayule-derived natural rubber – for the IndyCar Series, the IndyNXT Series and the IndyCar Autonomous Challenge, according to Krstolic. This means that the rest of tires contain the less-sustainable hevea natural rubber.
“We’re still working on scaling up production,” Krstolic says. “Once we have more material available, then it will be in more of our race tires.”
Because the guayule farms are not as well-developed as the hevea plantations, only the sidewalls of the new tires are made of guayule. Krstolic says the plan is to produce IndyCar tires entirely made of the home-grown natural rubber as soon as possible.
“If we prove it out in the sidewall, then we’re able to use it in other parts of the race tire,” Krstolic says.
So, what is the rest of the tire made of, if not guayule?
IndyCar tire treads, Krstolic says, are typically made of synthetic rubber. As of this season, the main building blocks of this synthetic rubber are monomers manufactured from hard-to-recycle materials, including used shopping bags and post-consumer film.
Bridgestone’s synthetic rubber is certified by the International Sustainability and Carbon Certification PLUS program, which validates that Bridgestone is using recycled materials.
The material made its debut in May, featuring in every – practice, warmup and race – tire used in the 2023 Indy 500.
However, before this season’s usage of the more sustainable synthetic rubber, Bridgestone relied on petroleum-based monomers instead.
Dutzik says “oil poses environmental threats and every step of the supply chain.”
Dutzik says oil – everything from drilling, transporting, refining and powering vehicles – has “huge impacts” on the atmosphere, including heavily contributing to local air pollution and creating greenhouse gasses that break down the ozone layer.
According to the U.S. Energy Information Administration, petroleum consumption averaged nearly 20 million barrels per day in 2021. The industrial sector made up 26.9% of all petroleum consumption that same year. The transportation sector, however, still accounted for the majority of petroleum usage.
Krstolic says there is still “a lot of improvement that can happen” in the future to continue to increase the sustainability of the new synthetic, recycled rubber.
“They’re needed in a lot of different applications in both tires and other areas,” Krstolic says. “Being able to start to source those from either recycled or bio content is a pretty big hitter.”
Despite Bridgestone Americas’ sustainability efforts, Savla is calling for the green technology to be made widely available to the public, and he is skeptical of the company’s practices.
“If they start releasing that data to the general public, there’s a lot of research that can be done there after that,” Savla said. “That will have a much bigger impact than just the IndyCar industry itself.”
However, Krstolic says testing guayule-derived rubber tires on the smaller scale within IndyCar is necessary and allows Bridgestone researchers to analyze whether the compound is a viable natural alternative.
“The goal for racing has always been proving out the technology at the most grueling stage of motorsports,” Krstolic says. “This guayule was really meant to go into passenger tires eventually, and racing was just the perfect place to showcase it.”
Bridgestone plans to have guayule-derived natural rubber tires available to the public by 2030.
“They should release the data if they are so confident in this,” Savla says. “If they can show that this technology works in those extreme conditions, that’s awesome.”
Before the company can make these tires available to the public, it needs to find a good way to recycle them.
For now, IndyCar is attempting to reuse any lightly used tires within pit stop competitions and other IndyCar-sanctioned events outside of racing before the wheels are finally discarded.
Once the tires are truly unable to be reused anymore, Bridgestone takes them to a facility that produces alternative fuel that powers the city of Indianapolis. However, there is very little information publicly available about this practice.
In the future, Krstolic says Firestone Racing wants to go even greener by creating “100% circular” tires that can be broken down and remade into new tires.
Although IndyCar is the only racing series to have embraced the use of guayule thus far, Guidotti says IndyCar has been in communication with NASCAR about how the series can improve its sustainability practices in the future.
“When it comes to sustainability, sharing is caring, right? We all have to move on this,” Guidotti says.
It is clear that IndyCar has come a long way, but the series has not waved the checkered flag quite yet on its sustainability journey. Rosenqvist says it is a “no brainer” to keep pushing forward with this new green technology.
“It’s not like we’re going to end here,” Rosenqvist says. “We’ll keep doing what we can to make sure we really leave a good footprint behind us.”