Russell: Hard compounds will be Mercedes' "only silver lining" in hot F1 Spanish GP

In the development of its W16 for 2025, Mercedes has invariably retained one of its key weaknesses from last season – poor thermal management, particularly at the rear axle.

Although this is actually beneficial in colder races, as demonstrated by its dominance of 2024's Las Vegas race, Mercedes is susceptible to overheating its tyres amid higher temperatures.

Both Mercedes drivers attempted long runs in FP2 on the soft tyre in an effort to work out a set-up to keep the tyres away from the realms of thermal degradation on Sunday – Russell did an 18-lap stint, Andrea Kimi Antonelli a 16-lap stint.

Russell felt that his results so far at Barcelona alluded to the idea that Sunday's race will be difficult, as the team had met its expected qualifying performance. However, given that the race is on the C1-2-3 suite of Pirelli tyres, the Briton was pinning his hopes on the idea that the hardest tyre would suffer less drop-off under overheating versus the softer grades of rubber.

"We know that on a Saturday our car is anywhere between P2 and P5, that's where it's been all season," said Russell, who qualified fourth.

"And again today, so it's good we managed to get to Q3 only on two sets of tyres, so I've got a new soft tyre tomorrow which is a valid race tyre, so that's a positive. But we're realistic, we know that the car isn't quick on Sundays.

Andrea Kimi Antonelli, Mercedes

Photo by: Peter Fox / Getty Images

"We also made a lot of changes to the car this weekend to try and improve the race pace, so to see that we haven't really hindered the qualifying pace is a positive. But then also it may mean it's not going to improve the race pace. [The race] is going to be an interesting one for us.

"We struggled a lot when it was the soft compound of tyres when it was hot, but when it was the hard compound of tyres in Bahrain and it was hot, we obviously finished second there. 

"So it's when the tyres overheat, let's say if the tyres overheat by 10 degrees on a C4, it's much more punishing than 10 degrees on a C1 tyre. So that's sort of the only slight silver lining to give us a bit of hope for tomorrow."

Antonelli concurred after qualifying sixth, although he drew attention to the long-run data that Mercedes had accrued over the Friday practice sessions.

The Italian felt that Mercedes' return to its usual Saturday form after a bruising pair of races at Imola and Monaco was partly down to rolling back on the suspension package it took to the Emilia Romagna round. He added that the team would need more time to get its head around the effects before reinstating it to the car.

"I think tomorrow is going to be really hard with the hot temperature and we'll see, but the goal is to try and keep those tyres [in the best possible condition].

"We've been doing a lot of long runs, we have quite a lot of data, but the others are also very strong.

"Coming back with a good quali pace, it felt quite together. Let's see if we can have that feeling in the race."