Yahoo Autos Solving GTP’s cold tire conundrum
The advent of the new GTP era has coincided with new sustainability initiatives with IMSA and Michelin, where tires are intended to survive multiple stints. While that result has been achieved, the consequence has been cars that are an absolute handful on cold tires.
“We used to say in DPi time, the nighttime with cold tires is tricky,” said Filipe Albuquerque, driver of the No. 10 Wayne Taylor Racing with Andretti Autosport Acura ARX-06. “It’s [now] way harder. It’s 10 times harder when the tire is out of the window to drive, and because the car is heavier, there is a bigger inertia to catch the car. All those things combined, it makes things so much harder.”
It was visibly evident in the early-season races, when a GTP car would leave the pits on cold tires and be slower than GTD cars in the corners for a few laps. It played a big part in Porsche Penske Motorsports’ victorious strategy at Long Beach, where the No. 6 963 went the entire 100-minute race on a single set of tires to avoid the cold-tire issue.
The reasons for the cold tire issues are numerous, but start with tires designed to last longer. And while it’s not just the GTP cars that are affected, they seem to be get the worst of it. Part of that may be due to the way the hybrid GTP cars use the tires and how they slow down — relying in part on energy harvesting and less on heat-producing friction. But as the season went on, it seemed to be less of a problem. Was that because teams and drivers were figuring out how to switch the tires on more quickly, or were there other factors involved? The consensus answer is, a bit of both.
“I think it’s been luck,” said Albuquerque’s co-driver Ricky Taylor. “We went to Watkins Glen and there was a session there where we probably spent five laps more than 20 seconds off the pace, just trying to get the car in the window, or you’re not surviving. And then in the race it heated up and it was like it was 2022 — just back to normal.”
Taylor says that the drivers have figured out some things, and the engineers as well, such as optimizing traction control in the early laps on fresh tires to get more heat into them, but that’s a small percentage. What’s really helped is warmer temperatures for the summer races, but the warmer races also mean a switch to a harder compound; for most races, IMSA teams have only one compound of tires.
“Certainly, as the season has progressed, and teams have accumulated miles, the GTP teams have come to learn more about these cars and tires in their first year of competition,” said Hans Emmel, Michelin’s manager for the WeatherTech Championship. “Teams have managed to find setup and TC compromises to help warm up, as well as out-lap strategies. That being said, tire warmup remains challenging and is a key focus of our next development loops.”
The challenge of tire warmup was on full display in the last outing at Road America. Alexander Sims crashed the pole-winning No. 31 Cadillac Racing V-Series.R in the morning warmup. Connor De Phillippi spun the No. 25 BMW M Team RLL M Hybrid V8 on the warmup lap, and then crashed only a few laps into the race. Cold tire issues are likely to rear their head again at Indianapolis this weekend, where temperatures are cooler than expected and much cooler than they were when teams tested at the track in July.
“For sure [warmer] temperature makes it so much easier, especially when we go to a good surface like it is [at IMS] or Road America,” said Matt Campbell, driver of the No. 6 Porsche Penske Motorsport 963. “It does, for sure, help a lot. But I feel like when we come back to tracks when it’s cool, especially later at night, we’re still going to be struggling quite a lot as we experienced sort of earlier in the year. So it’s gonna come full circle again. But I feel like we’ve also improved, let’s say, our warm-up phase and how we go about getting the tires up to temperature to also help this. But when it’s cool, I feel like everyone’s going to struggle the same amount.”
One of the challenges is that Michelin brings one compound to the races, and the decision on which to bring is made well in advance. The exceptions are Daytona, where teams have both Soft Low Temperature (SLT) and Soft High Temperature (SHT) compounds to use, and also this year for Watkins Glen, where teams were given the last-minute option to use the SHT due to temperatures being a bit cooler than expected. For the summer stretch from the Glen to Indy, the Medium High Temperature compound (MHT) is prescribed.
The difficulty of getting heat into the tires this year has certainly produced some drama. It’s also allowed some interesting strategy decisions as teams have come to grips with it. While some might be tempted to dismiss the complaints, it’s a real issue when drivers have to tiptoe for a few laps on fresh tires — not only for them, but for those in the cars around them as well. And when things go wrong, well, as Albuquerque repeats one quote he heard: “These pro drivers, the best in the world, look like amateurs.”
GTP drivers have to cope with significant drop-off in performance on cold tires, which can be a problem both for them and the drivers in other classes they are trying to get around. Jake Galstad/Motorsport Images
For now, it’s just something drivers will have to deal with and hope track conditions are in the right window for the compound to work optimally. But there needs to be a discussion about finding a solution, says Cadillac Racing driver Pipo Derani, who shares the No. 31 Action Express Racing machine with Sims.
“There are so many things that that go around what they’re trying to achieve with the tire,” Derani said. “What their goals are in terms of longevity and how they produce the tires, and if they’re more green, and so on. And that obviously has an effect on how they react as they’re new. It has been an issue from from the beginning of testing and still to today — one that, in my opinion, needs to be addressed.
“Obviously, there’s not much we can do to to make that particular issue much better, unless there’s something done by the either the championship or the tire manufacturer. This is not a criticism of the tire itself, because I think Michelin has always done a great job. It’s more about the goals — and if the goals are to have a tire that lasts X amount of stints, that’s obviously going to have a consequence in how they turn on.”
