(Motorsport-Total.com) – Formula 1 is a sport of thousandths of a second, where often the details are decisive, which remain invisible to the viewer on the television. A central battlefield for the engineers in the 2026 season is the aerodynamic and thermal use of the wheel rims.
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Since the regulations in this area again allow noticeable freedoms, the teams are working intensively to manipulate the operating pressure of the tires through innovative rim designs. Since the FIA strictly limits the hot air exhaust through the brake vents, the rim itself has become the decisive tool for heat exchange.
Pirelli motorsport chief Dario Marrafuschi emphasizes the immense importance of this development, which takes place behind the scenes: “The open regulations on the wheel rims are indeed an opportunity for the teams – perhaps not particularly visible to the general public on TV, but highly unmistakable,” he says in an interview with Motorsport.com Italy, a sister platform of Motorsport-Total.com in the Motorsport Network.
“The design of the rim has changed significantly compared to last year; we have seen rims with hollow spokes, which some teams call ‘pockets.’ This is precisely to facilitate, so to speak, the heat exchange with the cooling of the brake vents,” explains the Italian.
When using this thermal interface, the field is divided. There is no uniform solution, but rather two fundamentally different approaches closely linked to the aerodynamic philosophy and weight distribution of the respective car.
While some teams try to use the rim as an additional heat source to bring the tires faster into the optimal temperature window, others try the exact opposite.
According to Marrafuschi, this contrast is a deliberate strategic lever: “We actually see differences between the individual teams in who manages to control it – I wouldn’t say better, but differently. For one team, the goal may be to warm up the tire, while for another team it is about cooling it down, depending on the balance of the car. So we see differences here, and it is a significant performance lever.”
The Physics of Tire Pressure: The Key to Long-Run Consistency
The ultimate goal of these geometric plays on the rims is the precise control of tire pressure. A Formula 1 tire starts with a minimum starting pressure prescribed by Pirelli in the cold state.
However, once the car is on the track and the tires are working, the air temperature inside the tire rises drastically, which in turn increases the pressure. If this pressure rises too much or uncontrollably, the contact patch of the tire shrinks, grip breaks off, and the tire overheats.
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Whoever has the edge here controls the race over the distance. Marrafuschi explains the direct connection between rim geometry and consistency in the race: “They can effectively and efficiently control the pressure build-up from the starting pressure to the stabilized operating pressure.”
“When we look at performance and a jointly observed consistency in lap times – especially in a long run – it sometimes also depends on how well the team manages to control the pressure and keep it in the optimal window throughout the entire stint thanks to these devices.”
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The Grip Dilemma: Performance versus Physical Limits
From a physical point of view, a lower operating pressure is almost always desirable, as it allows the tire to mesh better with the asphalt and generate more grip. But the thermal load that the cars generate through their enormous downforce makes this an extreme balancing act.
“Generally speaking, a lower operating pressure is an advantage for grip,” Marrafuschi continues. “Depending on race pace or vehicle performance, some teams find it difficult to keep the pressure low because they generate a lot of heat in the tires due to high speed, while other teams face exactly the opposite problem. So not everyone does the same.”
“Apart from that, the design of the brake vents, brake drums, and rims offers a technical lever to tune the car so that the tires work in their optimal window,” he says.
Logistical Feat Behind the Scenes
For tire manufacturer Pirelli, the increasing variance in rim designs also means a significant logistical effort in the background. Each rim must be precisely matched to the tires, and the procedure for last-minute specification changes is highly complex – especially since handling slicks fundamentally differs from that of rain tires.
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Marrafuschi gives an insight into the internal processes at Pirelli: “We can handle the rim developments proposed by the teams; everything is regulated. When rims are changed, the FIA is of course informed, and – speaking purely within Pirelli’s area of responsibility – we are also informed, and for a very simple reason.”
“Slick tires are mounted at the racetrack, with new sets fitted at each race. Rain tires, on the other hand, when not used, especially at European races, are transported by Pirelli already mounted on the rim; they are not dismounted,” he explains.
The “Pairing” Procedure: FIA’s Digital Fingerprint
If a team decides to introduce a new rim design, this sets off a bureaucratic and technical chain. “If a team wants to change its rim specification for Spa, this process is carried out by Pirelli on site by removing the tire, changing the rim, and also informing the FIA,” explains the Pirelli motorsport chief.
“The reason for this – and this is a technical background information – is that the FIA knows about a unique association between the tire, the rim, and the pressure sensor mounted on the rim. This is a connection called ‘pairing,’ just like when you pair Bluetooth headphones with a computer. As soon as a rim is changed, the FIA must be informed.”
Since optimizing the rims has a significant impact on tire performance, voices in the paddock already fear an expensive development war that would have to be regulated again by the FIA from 2027 onwards.
Pirelli itself sees itself only as a service provider here and not as the driving force behind potential bans. Marrafuschi: “It is a regulated process that is manageable for Pirelli within the rules set by the association. So if rim development were to be restricted, it certainly would not be at Pirelli’s request, but for other reasons that are not Pirelli’s responsibility.”
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