How traffic shapes Williams’ cooling strategy at Mexico City

At the Mexico City Grand Prix, Williams must set its cooling level before it knows how much time each car will spend in traffic. Too little can leave a driver managing temperatures and losing time; extra cooling brings a drag penalty. That compromise gives Williams’ strategy group a larger role in setup decisions than on most weekends, says Charles-Antoine Florentin, the team’s head of race strategy.

At 2,250 metres above sea level, air at the Autódromo Hermanos Rodríguez is roughly 20% less dense than at sea level, and cooling potential falls by a similar amount. The turbo must work harder to supply air, while the brakes, power unit and larger electrical system shed heat less effectively. Teams need enough cooling for those demands, but each extra measure costs drag.

Florentin says Williams estimates how much traffic each car may face and when it is likely to arrive. A car stuck in a pack in the opening stint creates a different cooling challenge from one caught after the pit stops, since the wake of a rival raises overheating risk.

The layout adds another complication: dirty air through the middle-sector Esses and the Foro Sol stadium sequence can make it harder to stay close, and a following car may lose ground before reaching the long straight.

Ahead of the weekend, Florentin cautioned against treating Friday’s first readings as definitive. The surface begins with little rubber and changes as cars run; tyre degradation can fall sharply between practice and the race. He said Williams would use practice to compare the pace gaps between compounds, assess whether the soft could cover a worthwhile race stint and estimate how much the track would improve by Sunday.

Florentin also expected degradation to be slightly higher in 2026 than in 2025. But the 2026 C3-C4-C5 selection could put the hard closer to the medium than the C2 hard tyre used in 2025, he said, reopening a medium-to-hard one-stop option while keeping the soft as a race tyre.