IndyCar tweaks tire allocations ahead of 'cheese grater' Thermal Club

Today at 12:51 PM

Think of The Thermal Club's track surface as the 'Coachella Valley Cheese Grater.' No circuit on the IndyCar Series' calendar shreds tires at a faster rate than the sharp aggregate found at the private Southern California road course, and the trend will continue this weekend as the facility hosts its first championship motor race.

With Thermal's torturous track surface in mind, IndyCar is briefly stepping away from the new tire distribution policy it introduced at St. Petersburg, where teams received five sets of the softer and less durable alternate tires and five sets of the harder primaries. Thermal is back to an outlay of six primary sets and four alternates to give teams more of the longer-lasting tire compounds.

Working from a request by IndyCar to create a greater gap in performance between its road racing compounds, Cara Krstolic, Firestone's chief engineer and director of race tire engineering and production, and her team made the changes, which were on display to great effect at St. Petersburg.

With alternates that were quick but struggled to survive more than a dozen laps, the disparity in compounds was evident, and with the same call for primary and alternate separation at the remaining road and street courses, Firestone has made changes specific to Thermal's hungry 3.067-mile circuit.

"When we talked to IndyCar over the off-season, they said we need more interest coming out of the tires," Krstolic told RACER. "So, anything that we could do to widen the gap and make the alternate truly wear out, as opposed to having an alternate that’s pretty much there over a full stint, which was just not going to provide very good racing.

"So what we went through for Thermal is a little bit of a different approach. Instead of trying to make the alternate softer, as we did at our street courses, what we’re doing is putting more toughness into the primary tire.

“Even last year at Thermal, you saw quite a bit of drop-off, even with the primaries. So instead of trying to make the alternate softer, we’re making the primaries more durable, just giving them a little bit more toughness, more temperature resistance. So you’re still going to have the difference between the primary and alternate, but not quite to the level that you would see at St. Pete or the other street courses this year."

At last year's non-points 'All Star' race at Thermal, teams used harder Firestone compounds designed for heavier hybrid IndyCars, but due to the series' decision to delay the introduction of its energy recovery systems until July, there was a mismatch in vehicle weight — the cars were more than 100 pounds lighter than what the tires were designed to accommodate. That isn't the case in 2025.

Firestone's tires are matched to the cars, which have increased by 105 pounds from 12 months ago (the ERS units add just over 130 pounds, but have been offset to 105 by the adoption of magnesium bellhousings and transmission cases) as the field heads to Thermal for the first time in hybrid configuration.

"With Thermal last year versus Thermal this year, we have truly a different car," Krstolic said. "With the weight of the hybrid and the performance of hybrid, you’re going to see quite a different approach of the tires, you’re going to see a response to the tires. So we’ve got an alternate tire that is not too far away from what we raced last year.

"You will see a lot of drop-off because you have the additional weight. You have how the hybrid performs with this track and with this vehicle, so we will see some interesting performance out of the alternates. You’re still going to have a lot of drop off and degradation, but we will still have a good racing product. The engineering side of me likes that challenge, and our team is always up for a challenge."

After Thermal, IndyCar returns to California in April for the 50th running of the Long Beach Grand Prix where the split primaries and alternates will be five and five, and the rapid consumption of alternates is expected to continue. Based on driver feedback from the high-consumption alternates at St. Petersburg, the performance gap with Firestone's IndyCar tires will be an ongoing topic of interest this season.

"The drivers had mixed feelings on the alternates; some thought the deg (degradation) was too high where you had one or two qualifying laps before the tire started to drop off, and it was definitely a challenge to manage them during the race," Krstolic said.

"However, the goal from IndyCar was to have a tire that was going to drop off early and make some difference in the racing strategies. So we listened to what the drivers say. We take that feedback. It’s very important for us in our design cycle, but we also have the feedback of IndyCar, who has the overall quality of the race in their minds when they give feedback to us. So it's a little bit of a mixed bag of feedback, but I do think the drivers understood the direction IndyCar is trying to go. So all in all, we will see the same tires for Long Beach."