Pirelli has hit back at conspiracy theories about Ferrari's sudden return to the top in Formula 1 this year.
After three consecutive years of Mercedes dominance, it is now the red team that is clearly leading in 2017.
"At 25 points ahead, [Sebastian] Vettel is now clearly the world championship favourite," Mercedes team chairman Niki Lauda told Osterreich newspaper.
One theory is that Pirelli's new, wider slicks were designed with a narrow 'tyre window' that specifically suits the 2017 Ferrari.
"Why this Ferrari succeeds [with the tyre window] and we do not is probably an Italian mystery," said Mercedes team boss Toto Wolff.
Pirelli CEO Marco Tronchetti Provera has hit back at that intimation of Italian collusion.
"This is a discussion about the seriousness of the top three teams and how they tested the wider tyres with older cars," he said.
"Mercedes tested with Pascal Wehrlein, while it was Sebastian Vettel who took the responsibility for Ferrari."
Auto Motor und Sport also quotes Provera as saying: "Sebastian even took the time to visit us in the Milan factory several times to discuss his impressions with our engineers."
The season continues with the Canadian Grand Prix next weekend.
