If you’ve watched a Formula 1 race in the past 10 years, you’ve probably noticed that people within the sport tend to talk about the tires. A lot.
The 2010 Canadian Grand Prix is often referenced as the catalyst, when the Bridgestones could not complete a one-stop race and tire strategy made for a thriller. That blueprint was handed to Pirelli, with a request – make sure the tires degrade. A lot.
More recently, the drivers have asked for harder tires in order to be able to push more, and so we’re back to one-stop races despite built-in degradation. But it turns out that this year, that’s brought tires back into the spotlight again for a completely different reason: some teams can’t generate enough heat in the harder compounds, and keep it there.
“They are talking about difficulty in warming up the tires,” Pirelli’s head of car racing Mario Isola tells RACER. “I’m not 100% sure, to be honest. It could have been true in Shanghai where it was quite cold; we had Baku [where] if I’m not wrong, that was colder than in previous years. But in the last few races, the warm-up was not reported as an issue for any of the teams.”
As the only items connecting the car to the track, tires are always a great differentiator. But it has also been common to hear drivers complaining that the operating window of the Pirellis is too small. If you’re not in that window, you lose performance. The problem is, the window is constantly changing.
“To define the working window of the tire is not so easy,” Isola admits. “If you consider the curve of the grip, you always have a peak. You don’t have a warm-up phase, then a plateau and then the overheating phase. You have a curve and then you have a peak.
“So from the peak, you define the window that says how much grip you lose. That can be 1%, 2%, 3%… depending on the definition, you can consider the window wider or narrower. So we should define the window first.
“Then this window is affected by several factors. If we talk about running on track, there is the influence of the tarmac, the layout of the circuit, the level of wear on the tire, the weather conditions in terms of temperature, the set-up of the car, the downforce on the car, rim heating or rim cooling…
“If you are good at managing the temperature of the air inside the tire, you are basically managing the pressure, so you know exactly how the footprint is working. The level of complexity in which teams manage the tire is very, very high. They look after every detail. When you consider all these elements, they are all going to contribute to warming up the tire or overheating the tire, etc.”
Despite all of that focus on the tires, they remain tricky beasts to tame. Pirelli is confident it has delivered a range of compounds that overheat less than last year, suffer from fewer blisters and are spaced correctly in terms of lap time delta. So why the problems so far this year? Isola believes the answer lies in the new aerodynamic regulations.
“Last year the tires had certain characteristics; teams were probably focusing more on designing cars to be lighter on tires compared to last year,” he says. “Looking at the efficiency, opting for less drag instead of more downforce. At the same time, we were developing tires with different characteristics, but based on the targets that they’d asked for.
“These tires require a bit more energy to work properly, so we went in a direction, they went in a direction. We gave them the tires in Abu Dhabi, but obviously they tested them with a 2018 car that was different, so we had no complaints – everybody was happy with the tires.
“What is strange that we went to Barcelona for the pre-season test with the same tires – exactly the same tires, because the Abu Dhabi test was successful so we had no need to change anything – and we had no complaints. In Melbourne we had no complaints. Then they started to come later in the season.
“At this point it is impossible for us to make any adjustments because the regulation is clear. We cannot change. We can ask the FIA to change tires with their authorization only if there is a safety issue.
“So what happened for example last year, when for three events we asked for a different specification of the tire was that on these three specific tracks – Barcelona, Paul Ricard and Silverstone – they had been resurfaced. With new tarmac in Barcelona we experienced a lot of blisters, and every type of blister is not the same.
“There are small bubbles that are blisters, but they are not affecting the performance or the integrity of the tire, and these are acceptable. But sometimes we have big blisters where part of the tread is coming off, and this is not acceptable because in that case you expose the construction and you take a big risk. Therefore, you can have a tire failure. That’s why we asked to modify the specification for the three races.
“So it’s important to define the differences; why last year we decided to change for a safety issue for three races. This year, there is no issue. If I have to send a request to the FIA for a safety issue this year I have no idea what to write on the paper.”
Despite often being in the crosshairs when a team is looking for someone to blame for its struggles – Haas has been particularly vocal this season while it struggles to extract its car’s potential over a race distance – Isola says he welcomes constructive criticism.
“When you are the sole supplier, it’s quite common that teams are complaining,” he says. “What is important is that the criticism is made in a productive way and a positive way. So if we can understand and learn and direct our development in the right direction, it’s useful to have these kinds of complaints. Otherwise it’s not giving us any tools to improve, so it’s not useful.”
Pirelli assigns engineers to each team, and those engineers do not have access to data from any other car. That applies throughout the company – save for a handful of staff predominantly based in Milan – in order to ensure integrity. While the tire supplier understands the conditions under which its tires work best, different car designs and characteristics require a unique equation for each team.
“We have an idea because we analyze our compounds and know what is the best temperature for the peak of grip for each compound,” Isola says. “The problem is, when we talk about the temperature of the compound, we are always referring to the bulk temperature – the temperature that is inside the compound – and this is a temperature that you cannot measure.
“The surface should be at the same temperature to generate the grip. What happens is they measure the carcass temperature and they measure the surface temperature, but these two temperatures are not always at the same level. The carcass temperature is mainly due to the energy you are putting through the tire, [so] the surface can be affected a lot by the sliding or another aspect.
“So that’s why they then make an estimation of the bulk, they look after the carcass and the surface and then they make their calculations to find the best compromise in order to make the tires work.”
That challenge was almost changed in Austria, where the teams, FIA and F1 met to discuss returning to last year’s compounds. Unanimous approval was not forthcoming – much to the dismay of Ferrari boss Mattia Binotto – but Isola says it would have been a pointless change regardless.
“Going back to last year’s tires means having the same problems as we had last year, because the cars this year are quicker, and the lap time is telling you how much energy the cars are putting into the tires,” he says. “That’s why going back to last year’s tires – in my opinion – was not the right move.
“Then, if we want to have meetings and discussions with teams, drivers, the FIA and FOM to try and improve the show, we are more than happy to be involved, and to be part of that if we can do something with the tires as we have in the last nine years. But it’s not going back to last year’s tires that is fixing the issue.”
The trend in previous seasons has been for teams to start getting on top of tires as the season goes on, with car development tailored to extract more performance from them. Upgrades sometimes take months to deliver, so it’s not inconceivable that a change of tire could have made the situation worse when new parts designed around the 2019 compounds came through later in the year.
Either way, as all teams get the same tires in the same way they are handed the same technical regulations to work with each year, Isola says it’s just another aspect to highlight which outfits are capable of doing a better job.
“It’s not easy, it is a challenge. I believe it is quite interesting, it’s a technical challenge just like if you ask an aerodynamicist to find more downforce. It’s a part of how to use the package. Obviously the tire is the same for everybody, the information we give to the teams is the same for everybody, then it’s up to the team to find a way to use the tire in a better way.”