Firestone fired up for Indy 500

INDIANAPOLIS—When you see drivers oversteering down the straightaways at the Indianapolis 500, it's because the tires are designed to pull the car to the left. It's the little things that help a car stay above 220 mph in the turns.

Cara Adams, director of race tire engineering and production for Bridgestone Americas Inc. and Firestone Racing, spoke about the event and, more specifically, the Firestone Firehawk racing tires that will be used, via video from Indianapolis.

Despite pandemic-related distractions, when the green flag flies for the 104th Indy 500, the Firestone Racing Tire team will be focused on the track.

This year's Indy 500, which was held on Aug. 23, was delayed three months because of COVID-19. Bridgestone has been the sole tire supplier for the IndyCar Series since 1996. The current contract runs through 2025.

The Indy 500 is where Firestone really got its start back in 1911, Adams said.

"Here at Firestone, Harvey Firestone really realized the importance of racing that very first (Indy 500). The racing platform provided the opportunity for a brand not only to provide a proving ground for our tire development but also for a promotional platform for the tires."

She quoted Harvey Firestone's famous words, "Win on Sunday, sell on Monday."

Pulling to the left

"All four tires on the car are different," Adams said. "... While they look the same, the construction and compound is different."

The compound for this year's Firehawk is the same as the 2019 version, she noted.

Since the drivers constantly are turning left on the oval track, the load on the tires is much greater on the right side of the car. To compensate, the tread on the left side tires is 3/10ths inch thinner than the right, which makes the car pull left.

The left side tires also are more pliable, especially on the sidewall, Adams said. The right side tires need to be stiffer and more durable to handle most of the load.

Adams illustrated how the tires are impacted in Turns 1 and 2 at IMS.

A driver enters the 90-degree Turn 1 at more than 220 mph, and the downforce created by the aerodynamics of the car increases the weight on the tires by more than two and a half times the weight of the car when sitting still.

When in the turn, Adams said, the left side tires will carry less than 30 percent of the load of the vehicle.

The tires react in Turn 2 similar to Turn 1, but with slightly higher loads as the corner entry speed is close to the mid-corner speed, and the car remains more settled, according to the presentation.

Adams said when the car is in Turn 2, the total area of contact between the tires and the track is less than two sheets of notebook paper.

She added that most cars don't run below 220 mph while making the turns.

Firestone Firehawk

Thirty three drivers competed in the 200-lap, 500-mile race.

Bridgestone brought around 4,400 Firestone Firehawk racing tires to Indianapolis for the event.

For the actual race, Adams said the teams have 10 sets of tires per car. Racers change tires about every 30 laps, and need about eight sets, she said. The other two sets are in case of an emergency or if there's an opportunity for an extra pit stop.

Adams noted that despite having 10 sets of tires, most race teams carry only six to eight sets of wheels. So, when a set is pulled off a car, the Firestone team mounts new tires on the wheels.

Adams said production on the IndyCar Series Firestone tires begins in December each year. Earlier in the year, race tire production was idled for about six weeks due to the COVID-19 pandemic.

Despite the challenges of this year's race, Adams said the Indy 500 always is a huge race for the company, especially for her team of engineers.

"We love this race. We are so proud of it," Adams said. "… We're so glad to be able to showcase these tires."