Valtteri Bottas returned to the Mercedes F1 cockpit on Wednesday, 30 October 2025, to spearhead Pirelli’s final private tyre test for the 2026 season at the Autódromo Hermanos Rodríguez in Mexico City. The Finn, already confirmed as a Cadillac F1 driver for 2026, sampled the softest C3-to-C6 compounds on a modified Mercedes W16 shod with experimental 18-inch slicks that are 25 mm narrower at the front and 30 mm narrower at the rear—key changes written into the 2026 technical regulations.
Bottas logged 112 laps (483 km) in morning temperatures that pushed track-side thermometers past 50 °C. Reserve driver Frederik Vesti, who had already run in FP1 two days earlier, took over for the afternoon and added 49 laps (210 km). Between them, the Mercedes duo accumulated 161 laps and 693 km of high-quality data for Pirelli’s engineers.
Tuesday’s running was entrusted to Stake Sauber and McLaren junior Gabriel Bortoleto. The Brazilian rookie racked up 136 laps (585 km) in a C45 chassis similarly adapted for the 2026 tyre dimensions, ensuring rear-to-front aero balance shifts and thermal degradation profiles were captured in representative Mexican heat.
The two-day programme delivered a combined 1 278 km of telemetry, the last private mileage before the official December 9 collective test in Abu Dhabi. That session, held 48 hours after the 2025 season finale at Yas Marina, will see all ten teams validate the definitive 2026 Pirelli compounds and narrower tyre architecture that will underpin Formula 1’s next regulatory cycle.
Source
- Davoine, Basile. (October 30, 2025). Valtteri Bottas a repris le volant de la Mercedes. Motorsport.com. Retrieved October 30, 2025, from https://fr.motorsport.com/f1/news/bottas-repris-volant-mercedes-2026/10772617/