The tyres
Three colours per weekend, but six compounds in the range. Which three are chosen decides how the race can be run.
The C1–C5 range
C1 is the hardest and most durable compound, C5 the softest in the regular range. Ahead of each weekend Pirelli nominates three steps – usually adjacent – and gives them the weekend's colours: white (hard), yellow (medium), red (soft). At circuits with high lateral loads and abrasive asphalt (Silverstone, Suzuka, Barcelona, Zandvoort) it is C1/C2/C3; at low-energy circuits such as Monaco, C3/C4/C5. The same physical tyre can therefore be the weekend's soft at one circuit and the weekend's hard at another.
Why it matters to the model
The degradation in the library is taken from previous races at the same circuit. If Pirelli has shifted a step between years, the comparison must be made per C-code, not per colour – otherwise the wrong rubber is being compared. The timing data does not contain the C-code, so the nominations are entered by hand.
2026 nominations
What the races show
Degradation is not a property of the compound alone but of compound × circuit × generation. The 2026 tyres degrade 1.3–3 times faster than the 2025 tyres at the same circuits (Barcelona 3×, Monza 2–3×, Zandvoort 2×) – a generational shift, which the model handles with a season factor until 2026's own races cover the circuits.
How many tyres, and when they must be used
On a normal Grand Prix weekend every driver is allocated 13 sets of dry tyres: 2 hard, 3 medium and 8 soft, plus 5 sets of intermediates and 2 of full wets (B6.2.4). Two weeks before each race the FIA names the softest compound as the mandatory tyre for Q3, and up to two mandatory dry-weather specifications for the race (B6.1.2). Normally six sets must be returned during the three practice sessions, two after each. If both FP1 and FP2 are declared wet or cancelled, one of the sets normally returned after FP2 may instead be kept until after FP3 (B6.3.8).
In the race each driver must use at least two different dry compounds, at least one of them a mandatory race specification, unless that driver has used intermediates or wets at some point in the race. When the FIA names two mandatory race specifications, that does not mean both must be used: the rule asks for two different dry compounds, of which at least one is on the mandatory list. Breaking the rule means disqualification; if the race is stopped and never restarted, 30 seconds are added instead (B6.3.6). That is why a driver who started on intermediates at Sepang was free to run slicks of only one compound for the rest of the afternoon. If the formation lap starts behind the Safety Car under the wet-weather start procedure, or a suspended race is resumed under the corresponding Safety Car procedure, wet-weather tyres are compulsory until the Safety Car's orange lights go out and it returns to the pit lane (B6.3.7).
Sprint weekends
Six weekends in 2026 carry a sprint: Shanghai, Miami, Montréal, Silverstone, Zandvoort and Singapore. There is one practice session, and one set fewer: 12 sets of dry tyres, 2 hard, 4 medium and 6 soft, with 6 sets of intermediates (of which 5 may be used) and 2 of full wets (B6.2.4, B6.3.4).
| Session | Tyre rule | Article |
|---|---|---|
| FP1 | Free. One set handed back within two hours | B6.3.9a i |
| Sprint qualifying SQ1 | At most one set, and it must be a new medium | B6.3.9a iv |
| Sprint qualifying SQ2 | At most one set, and it must be a new medium | B6.3.9a iv |
| Sprint qualifying SQ3 | At most one set of soft. New or used: the rule says soft, not new soft | B6.3.9a v |
| Sprint (at most 100 km, about a third of a Grand Prix) | Free choice of compound. The two-compound rule applies only to the race, so there is no mandatory stop. Afterwards the set that did the most laps in the sprint is handed back | B2.3.2, B6.3.6, B6.3.9a ii |
| Grand Prix qualifying | Free choice. Three sets handed back when the cars are covered for the night | B6.3.9a iii |
| Grand Prix | Normal rules: two dry compounds unless intermediates or wets were used | B6.3.6 |
If FP1 or sprint qualifying is declared wet, a driver who used intermediates in either session receives one additional set, and must return a used set after sprint qualifying. A driver who used intermediates in the sprint may also receive an additional set, but only if none was allocated earlier; that set cannot be used before the pit lane opens for the Grand Prix. No driver receives more than one additional set under these provisions (B6.3.9b). The cars are sealed within two hours of the end of sprint qualifying and the seals may come off three hours before the sprint's formation lap (B3.4.2); set-up can be changed again before Grand Prix qualifying.
What the allocation does to Sunday
Five of the twelve sets are handed back during a sprint weekend, so at most seven reach the race, and most of those are already used. Count the mediums: four sets, two of them spent new in SQ1 and SQ2 by every driver who reaches SQ2, and most drivers start the sprint on a third, which is then the set they hand back. That leaves one new medium for the Grand Prix. A plan that needs two fresh mediums on Sunday is usually not available on a sprint weekend; the planner on this site takes the allocation into account when you choose a driver.
In the five sprints so far in 2026 roughly nine cars in ten started on the medium. The softs went on cars at the back with nothing to lose, the hards on a handful trying to run the whole distance. With no stop and only 17 to 24 laps, the sprint is close to a procession: starting position predicts the finish far better than in a Grand Prix. Sprint qualifying and sprint results are under Results, with the sessions SQ and Sprint for each sprint weekend.
Source: FIA 2026 Formula 1 Sporting Regulations, Section B, Issue 09 (1 October 2026), Articles B2.3.2, B3.4.2, B6.1.2, B6.2.4 and B6.3. Tyre use in the sprints from our own timing data.
New tyres at the start
A softer starting tyre gives grip when the field is at its tightest. The model allows roughly half a second for the soft and closer to six tenths for the hard on the opening lap, and a halved overtaking threshold in the chaos of the start – which is why a simulation that favours starting on the hard should always be scrutinised.