The 107th Running of the Indianapolis 500 presented by Gainbridge has another small element that is another step toward a big impact, and it comes courtesy of a collaboration between Firestone and Shell.

An impressive total of 4,500 race tires have been supplied this month to NTT INDYCAR SERIES for practice, qualifying and Sunday’s 500-mile contest. While the Firestone Firehawk construction and compound design are the same as the tires used in last year’s Indy 500, one small key component is making a big impact toward increased sustainability efforts – along with a slightly softer compound with added grip.

The Indy 500-specific race tire will incorporate a synthetic rubber created with ISCC+ certified recycled butadiene, a monomer produced with recycled post-consumer plastic waste, such as used plastic shopping bags, film, stretch wrap and other flexible polymer packaging. The tire was developed in partnership with Shell, which also innovated the 100% Renewable Race Fuel that also is new to North America’s premier open-wheel championship in 2023.

“When we build a tire, there are certain compounds that we need to make sure that are exactly the same,” said Cara Krstolic, director, race tire engineering and manufacturing, chief engineer, motorsports at Bridgestone Americas. “So, we monitor recipes and monitor formulations, but when you're looking at something like butadiene, it doesn't come in and say: ‘I'm from a natural source. I'm from a sustainable source.’ It doesn't matter what it is. It’s just in there, and it's just a raw ingredient. If we were to change something … then it actually might be different with how it is. But because this is a monomer, it's basically a fundamental building block. It doesn't matter how it’s sourced.”

This specific updated tire also was used during last month’s Open Test at Indianapolis Motor Speedway.

The change to a recycled source for the ingredient pushed back Indy 500 tire production closer to January, but Krstolic said it wasn’t “really a large change for us.”

“It's been something that we've been really proud of being able to put into our race tires,” she said.

Krstolic also provided some insight into Firestone’s guayule tire, an eco-friendly natural rubber compound derived from the guayule shrub and used in the alternate tire at each of the street circuit events this season.

The guayule tire debuted last year at the Music City Grand Prix in Nashville, the only race where it was used in 2022. This year’s race total for the tire has increased to the five street races, but it still will be some time before guayule is used in the construction of the tires at every round. Still, Firestone is fully committed to the project.

“At this point, we were still ramping up our supply,” Krstolic said. “So likely for next year, we'll see only street courses again. …We’ve done a lot in talking about why guayule, and now the next step is to get more farmers to be able to plant the crop.

“At that point, we’ll get up to full-scale commercialization and then we'll not only see it in the INDYCAR tires but also passenger tires.”