IndyCar Nashville finale: Everything to know about alternate tires on oval tracks

IndyCar Nashville: What are alternate tires?

In IndyCar, tire supplier Firestone has created four different tire compounds for modern racing: Primary (blacks), alternates (reds), guayule alternates (greens), and rain tires.

Primary, or black, tires are the main compound used on every type of race track: Oval, road, and street. They’re the do-all tires that can handle the fastest superspeedway or the most fiddly street circuit, and they’ll be the preferred tire for any race. Traditionally, only primary tires will be available on oval tracks.

Alternate, or red, tires are made of a softer rubber compound than the primary tires. Drivers on red tires will be able to corner better and hit faster speeds — but only for a limited time, as this compound wears much faster than than the primaries. Alternate red tires are traditionally used on permanent road courses — though this compound will be introduced in Nashville for the oval finale.

Alternate green tires were introduced by Firestone in 2023; these tires are made from a natural rubber extracted from guayule shrubs in Arizona and represent a much more sustainable form of rubber. Like the alternate reds, the alternate green tires are designed to wear faster than the primaries. They’re only available on street courses.

And that leaves us with rain tires — which are exactly how they sound. Rather than having a slick surface, these tires are grooved to allow for rain to pass through the treads and offer better grip. Rain tires are never used on ovals, as the high speeds are too dangerous, even for a grooved rain tire.

Why aren’t alternate tires common on ovals?

Alternate tires aren’t already common on oval tracks for a variety of reasons.

First and foremost, only developing one set of tires to race on ovals is more affordable than introducing multiple compounds. Oval tracks subject tires to some seriously impressive forces; designing and producing a tire capable of standing up to those forces is challenging in and of itself.

The moment you have to start testing a second compound on ovals, costs naturally rise. Track rental is expensive, as is flying drivers and teams out to that track for a private test. And that’s not even accounting for all the data that Firestone has to collect, analyze, and implement back at its headquarters to develop a second compound and understand how teams can effectively — and safely — use it.

Safety is another big factor. Oval tracks are notoriously dangerous, in large part because drivers and cars hit such high speeds, and because the tracks are generally lined with barriers and not runoff zones. If a driver loses control, he’ll likely do so at high speed, and the only thing waiting to catch him is a fence and some SAFER barrier.

Because of that, you want a tire that is guaranteed to stand up to those forces. You don’t want any surprise failures, and you don’t want the tires to wear too quickly. It’s a delicate balance, and tire manufacturers like Firestone stay busy reworking the primary compound to best suit ovals.

Alternate tires are intentionally designed to be softer and wear faster, which can make their implementation on an oval seem antithetical to the “safety” argument — but IndyCar thinks it’s figured out a way to bypass those concerns.

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Why is IndyCar introducing alternate tires for the Nashville finale?

There are plenty of factors that go into the introduction of alternate tires at Nashville Superspeedway — with the first of them being the fact that Nashville Superspeedway wasn’t initially intended to be on the IndyCar calendar.

IndyCar’s initial race calendar ended the season in downtown Nashville, on a slightly altered version of the street course the series has been implementing for several years. However, the city of Nashville has been engaging in work on the streets IndyCar intended to use for its track; it was clear that a different track would be necessary.

To avoid too much disruption, IndyCar scheduled its finale at Nashville Superspeedway instead — a track that the series hasn’t raced at in 16 years!

Due to that, the series brought out a handful of drivers to the track back in June for some preliminary testing. The goal was to see how these new IndyCars would be able to race on the track, and how the Firestone tires would hold up.

Those drivers initially reported some concerns with tire wear on the primary tire; Firestone illustrated some durability issues due to the rough track surface, and that abrasive surface promised to translate into processional racing where overtaking would become difficult.

Firestone heard the concerns and responded in kind. In just a few months, the manufacturer developed a more robust primary compound but also determined that the addition of an alternate compound would create a more intriguing race.

It implemented an alternate tire for 2023’s oval race at Gateway, with promising results. Now, the series will kick it up a notch by introducing the alternates on a much larger track.

“The goal for the alternate tire is to have significant wear and degradation to the point that team pit stop strategies could change as tires may wear before the end of a fuel stint,” Cara Krstolic, Firestone’s chief engineer and director of Race Tire Engineering and Production, said in a press release.

“They are also designed for the different grip levels of the two types of tires to aid in creating more passing opportunities.”

The short answer as to why IndyCar implemented these tires? More on-track passing.

What will the Nashville finale alternate tire strategy look like?

Every single IndyCar team will receive a total of 10 sets of tires. Six of those sets will be the primary compound, while four will be the alternate compound.

There are no rules about how teams implement these tires in practice or qualifying. On race day, however, teams must use one set of primaries and two sets of alternates.

In addition, drivers have to complete two laps on each set of tires before they can change them. Only after completing two laps will the tire usage count.

Further, many IndyCar events require drivers to run a few laps in practice or qualifying on a set of tires, then use those “used” or “scuffed” tires in the race itself. With plenty of experimentation already at play, those rules have been scrapped for Nashville.