Formula 1 for dummies: how tyres are chosen for a gp?

Tyres are a key element in motor racing, especially in Formula 1 where hundredths, even thousandths of a second can be the determining factor. Tyre usage during a Grand Prix is defined in the Sporting Regulations, but how are the three dry compounds chosen? What criteria determine which compounds are nominated as the Hard, Medium and Soft? The choice is made by Pirelli, in consultation with the FIA and F1 and of course, safety is the paramount consideration, followed by the characteristics of the track and the expected temperatures, while data from previous races and simulation work also help inform the choice. Then the idea is to choose a combination of compounds that offer the greatest number of possible race strategies with the aim of delivering the best show on track.

As for the circuit, these are the characteristics taken into consideration, seen through the following parameters that Pirelli produces before each Grand Prix:

• abrasiveness of the track surface: indicates how abrasive is the asphalt and therefore how it impacts tyre wear;

• track surface grip: indicates what level of grip can be expected from the track, based on the characteristics of the particular type of asphalt used, as well as external factors such as the possible presence of sand, or how often the circuit is used – is it a permanent facility, a street circuit or a mixture of both?;

• traction: indicates what demands the circuit layout makes at points where traction is required, i.e. when the tyre has to drive the car forward, especially on the exit of slower corners;

• braking: indicates what demands are placed on the tyres working in conjunction with the brakes when required to slow the car;

• lateral forces: indicates how demanding is the circuit in terms of the lateral forces exerted on the car, especially in the corners. In this instance, the tyres must keep the car on the racing line, resisting the forces trying to push it towards the outside of the corner at high speeds;

• stress: indicates the amount of load and speed to which the tyres are subjected on the circuit;

• downforce: indicates the level of aerodynamic downforce that pushes the car into the track. Downforce varies depending on how the teams set up the wings and other aerodynamic elements;

• track evolution: indicates how much track conditions change over the course of the weekend as rubber from the tyres is deposited on the track. This aspect is directly linked to the level of abrasiveness of the asphalt and which compounds have been chosen.

Once the three dry weather compounds have been selected from the range homologated for the season (in 2025 they range from the hardest, C1, to the softest, C6) each team is at liberty to choose its own strategy in order to make the best use of them over the race weekend. In general terms, the hardest compound nominated (the P Zero White hard) would be chosen to do the most laps because it is subject to less degradation and offers greater durability. This compound will be preferred at circuits with a very abrasive surface, if temperatures are particularly high and if there are several points on the track where the tyres are subjected to high loads. The P Zero Red soft is at the other end of the scale: it warms up more quickly and ensures a larger footprint and better grip. This is the tyre that delivers the fastest lap times and is therefore the obvious choice for qualifying. However, these characteristics mean it is also the tyre with the least durability and the softer the compound the less time it will last. Finally, the P Zero Yellow medium (C2, C3 or C4) is the most versatile of the three, occupying the middle ground between hard and soft, ideal for stints in the race when the teams are looking for a balance between durability and speed.

Every Friday, after FP2, based on lap times set during the sessions, one can estimate the performance difference between the compounds over a long run. This is done using the data acquired, cross-referenced with that from pre-event simulations, taking into account the weather forecast for the remainder of the weekend. Understanding the performance difference between the compounds is a vital part of race preparation. Each team plans how the race will unfold and which compounds will be used when, to get the best possible result. The regulations state that at least two of the three available compounds must be used in the race. Working on race strategy will have begun well before the event and it evolves over the course of the weekend, based on the data acquired. Where one qualifies plays a key role in deciding on strategy. Grid position is very important, combined with the ease or otherwise of overtaking at any particular track. Clearly, starting from the back at a tight, twisty track like Monaco is much more of a disadvantage than at Baku or Spa-Francorchamps.

Before the race, the teams come up with the optimal plan for their drivers, with a pit stop window that should deliver the best possible result. Usually there are three or four other options, as well as a detailed plan to deal with unforeseen events, such as a Safety Car period. Furthermore, the strategy is then constantly updated in real time depending on what is happening on track, the pace of one's drivers and that of the others, as well as the traffic situation. These days, input from the remote garage back in the factory is ever more important, but still, the feedback from the driver and their ability to understand their potential pace if running in clean air is vital.

For a race weekend, each driver can use 13 sets of dry weather tyres ( two Hard, three Medium and eight Soft), along with five Intermediate and two Full Wet. This allocation changes slightly for Sprint Race weekends: a total of 12 sets are supplied, split into two Hard, four Medium and six Soft.