The issue of racing in wet weather conditions continues to be a puzzling challenge for the FIA in the world of Formula 1. Despite Pirelli’s consistently high-quality work as the sole tyre supplier for the championship, the core problem remains unsolved. Formula 1 cannot afford to be a racing series where rain effectively halts all on-track activity under the blanket justification of safety concerns. To avoid such scenarios, intervention must target the only component of the car that actually touches the asphalt: the tyres. This is a matter that the Italian tyre manufacturer, Pirelli, takes very seriously and holds close to heart.
Why are teams reluctant to use the full wet compound?
It is well known among insiders and technical experts that tyres are not the only factor responsible for the heavy spray that eliminates visibility during wet races. Other aerodynamic components, such as the diffuser, significantly contribute to the issue. The Venturi effect produced by the diffuser increases the amount of water that is vaporized and thrown into the air. Given that current Formula 1 cars are effectively “ground-effect” machines, making substantial modifications to the rear diffuser is extremely complex without introducing equally effective alternatives. One such attempt—wheel covers—was tested several times but ultimately discarded, as they never truly convinced teams or the FIA due to their ineffectiveness.
As the exclusive tyre supplier, Pirelli has been studying a range of potential solutions for quite some time, all aimed at improving the tyre’s ability to evacuate water collected from the wet track surface. Although the sport is entering a period in which wet-weather car performance remains an area of uncertainty, the key objective is to make the full wet tyre a viable and functional choice once again. Teams across the grid have now largely come to the conclusion that extreme wet weather tyres are rarely useful during actual racing scenarios.
Typically, any use of the full wet compound ends with the intervention of the Safety Car or even a red flag stoppage, turning the whole exercise into a pointless delay. During the 2025 Formula 1 Belgian Grand Prix weekend, Mario Isola, who serves as Pirelli’s Head of Motorsport for Formula 1, was asked about this critical issue. He outlined the two main directions the company is currently exploring to address the challenge. Essentially, there are two strategic paths: either a single, all-weather wet compound, or two wet compounds with performance characteristics that are much closer together.
A single wet tyre compound? FIA regulations prohibit it
The first of the two approaches—introducing a single wet-weather compound—is not currently permitted under the FIA’s technical regulations. The rulebook of the FIA, which serves as the governing authority of Formula 1, requires that Pirelli provide two separate wet-weather tyre compounds. The reasoning is straightforward and tied directly to the need to guarantee on-track spectacle. Any regulatory change that could reduce the variability and strategic unpredictability of a race is essentially ruled out.
Formula 1’s rulemakers seek strategic variability, which a single wet compound would be unable to deliver. Nevertheless, Pirelli has already been actively testing this single-compound wet solution in other series, such as Formula 3 and GT championships, where the results have been consistently promising. Despite these successes, Formula 1 leadership remains unconvinced. A single wet compound would narrow the tyre’s range of optimal operating conditions, something the sport’s decision-makers view as a negative.
The proposed tyre would need to be a compromise between the current intermediate and full wet compounds, but this compromise could lead to underperformance in both very wet and semi-dry track conditions. That’s the core of the argument against it. However, adopting a single wet tyre could significantly help teams when it comes to data collection and tyre characterization—both of which are crucial for developing an effective race setup. More importantly, it would ensure that there is always on-track action, which should be the ultimate goal.
Bringing intermediate and full wet operating windows closer
The more likely and preferred path for the future is to revise the characteristics of the current compounds to bring their respective operating windows closer together. However, as Mario Isola himself emphasized, one major issue remains: determining how far conditions should deteriorate before race officials declare the track undriveable. This matters because such a decision could render the full wet tyre irrelevant right from the start.
The fundamental problem lies in the difference in water dispersion between the two wet compounds. At a speed of 300 kilometers per hour, the intermediate tyre is capable of evacuating around 30 liters of water per second, while the full wet tyre disperses approximately 80 liters in the same time. The disparity is significant, and Pirelli’s research and development department is working to narrow this gap in order to make both compounds genuinely usable in real-world racing scenarios.
The goal is to improve the intermediate compound’s effectiveness in damp conditions, while also expanding the full wet tyre’s usability beyond its current operational ceiling. This would allow for a smoother transition—or “crossover”—between wet compounds and slick tyres during changing weather conditions, improving the strategic landscape and ensuring more consistent on-track activity.
However, drivers could face difficulties bringing these redesigned wet-weather tyres up to operating temperature, particularly the full wet compound. This is due to the different tread height and groove geometry, which are likely to be revised to reduce the volume of water dispersed. These changes would also reduce the movement of the tread blocks—also known as “tread lug deformation”—which, in turn, influences the amount of heat generated through friction. By improving thermal behavior and limiting excessive tread movement, Pirelli could deliver a more stable tyre with more predictable wear rates.
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