What Tires Do IndyCar Race Cars Use?

In the world of professional motorsports, every component of the car is critically important, but among the very top, most important and unmissable elements are of course the tires that each car rolls upon. Many motor enthusiasts are fascinated by the differences in tires between different motorsports, and today we’re taking a closer look at the tires used in the world of IndyCar racing.

Since 2019 IndyCar has used the Firestone Firehawk tire. Since 2000 IndyCar has used Firestone racing tires almost exclusively citing working with one manufacturer helped with safety and supply. There are three types of tires, Primary Black – balanced, Alternate Red – faster and softer and Rain tires..

There is more than a little history behind the use of tires in the IndyCar series which we explore in more detail in the article below.

Background: The Groovy Past of IndyCar Tires

The first tires used in the Indy Race of 1911 were 4.5 inches in width and made by Firestone. They were used on cars like the Marmon Wasp, the car driven by the Indy Race’s first ever winner, Ray Harroun, who hit speeds of 75.59-mph. Since then, there have been consistent and concerted efforts to develop and improve IndyCar tires to make the sport both more enjoyable and safer.

In 1965, the tires doubled in size to 9.2 inches and stayed there for around the next 30 years or so. Different producers like Firestone and Goodyear made custom tires for different teams, but that size factor was generally consistent. The big thing that changed was the way the tires were constructed to that size, shifting from crisscrossing fabrics around a core to the radial design that we’re more familiar with today.

Other innovations and changes to the car design also informed IndyCar tire construction, such as the addition of a bolt-on wing to the car in 1972. This created a huge amount of additional downforce and added up to 20-mph extra speed to the cars.

Tire makers had to quickly adapt to that change, and they did with the aforementioned radial construction, which allowed for much better grip on the track.

Another key innovation was slicks. Around 1970, tire makers were still carving grooves into their tires by hand in order to provide better traction and protection from the dust and other debris that found its way onto the track.

As tire innovation sped up, producers found less and less time to make grooves, and in the end decided to try the tires as slicks. Formula 1 star turned IndyCar superstar Mario Andretti remembers the first time he was sent out in slicks:

However testing these indyCar tires was always going to involve trial and error and he also remembers the only time he was knocked out in 1974 when the right rear tire failed in a radial test at the 2.5 mile Ontario Motor Speedway, when he hit the wall backwards at 185 miles an hour!!!

Firestone and Modern IndyCar Tires

We mentioned earlier that in the early days of IndyCar there was competition between tire makers like Firestone and Goodyear, but since 2000 things have been quite different. Over the past 22 years, Firestone has been the sole supplier of tires for the IndyCar Series — since 2019 known in full as the NTT IndyCar Series, NTT being the chief sponsor, Nippon Telegraph and Telephone).

Far from being an arbitrary choice, Firestone’s history as a tire company is closely linked with that of the IndyCar Series. As we mentioned above, the very first Indy Race winning vehicle, the Marmon Wasp, was riding on Firestone tires. Each season, Firestone now provides anywhere from 20,000-30,000 tires to teams. Some 5,000-6,000 of which are used for the Indy 500.

One interesting aspect of IndyCar tires is that each tire on an IndyCar vehicle is just a bit different.

Right-front tire: stiff
Right-rear tire: stiff, matched to the front, ⅓ of an inch bigger than rear-left

The two right tires provide durability and consistency.

Left-rear: softer, ⅓ of inch smaller than rear-right – 15-inch tread
Left-front: bears brunt of grip – 11 inch tread

IndyCar tires are a complex construction, too, made with fabric, steel, and more than 10 other different compounds. When asked why IndyCar would allow one provider to monopolize supply, IndyCar President Jay Frye claims that the biggest benefit is that it allows the NTT IndyCar organization to work more closely with Firestone on safety and maintaining steady supply. In addition, it makes sense that if 1 supplier is delivering all the tires, no team can accuse another of an unfair advantage.

So what tires are the new standard in the NTT IndyCar Series? The answer is the Firestone Firehawk tires.

IndyCar and Firestone Firehawk Tires (2019)

The Firehawk tire was first introduced in 2018 and has been the standard tire since 2019. The tires come in 3 main varieties, namely:

Primary Black – Black sidewall; balance of speed, cornering and durability; used on all types of track.
Alternate Red – Red sidewall; softer than primary tires; faster speeds and better cornering; they wear faster; only used on road and street tracks.
Rain – Gray sidewall; developed and used especially for wet conditions; have a grooved tread pattern to boost traction and prevent hydroplaning; used on street and road courses only.

The rain tires are not used on oval tracks because in wet conditions, oval track races, like in NASCAR, are canceled or postponed. During any race, when an IndyCar driver pulls in to make a pitstop, a skilled and experienced crew can change the set of 4 tires in just 5 seconds, while adding 18.5 gallons of fuel in just 7 seconds for a total average stop time of an eye-watering 8 seconds.

In engineering terms, the key design innovation on the Firehawk is that it has been optimized for load dependency by allowing the rubber to change shape where it meets the road. The result is a more consistent grip on the road.

Who Makes NASCAR Racing Tires?

Why Tire Choice Matters

IndyCar is a strictly regulated motorsport, which leaves teams little room on how to update and modify their vehicles. One area they do have some flexibility, however, is with the tires that the car runs on. For this reason, the Firestone tires that are on offer come with a range of different tire pressures, which teams can use to suit different drivers and situations. They can also select from different tire compounds that deliver different levels of stiffness.

As we discussed further above, back in 1970, key innovations would mean massive changes to the way that IndyCar vehicles worked, such as the addition of the bolt-on wing.

Dramatic shifts in the driving dynamics demand new innovations and changes to tire engineering. Since the cars themselves are now quite standardized, the scope for tinkering is reduced when it comes to gaining a speed advantage on the track. Tires therefore are a critical element of remaining flexibility that teams are able to exploit.

Final Lap

So while NASCAR is the supplier for NASCAR, Firestone is now the supplier for IndyCar. There have been some changes throughout the decades, as is expected in a motorport with such a long history, but for now its looks like the Firestone Firehawk will be the indyCar tire of choice for a good few years to come.

References

https://en.wikipedia.org/wiki/Ray_Harroun

https://www.firestonetire.com/our-tires/brands/firehawk/