Pirelli will undertake structural changes to its compounds to avoid blistering at certain tracks following a request from Mercedes.
According to Auto Motor und Sport, the German manufacturer consulted with Pirelli during pre-season testing in Barcelona in order to address the issue of extreme blistering of its tyres.
The Silver Arrows outfit suggested a reduction of the thickness of its rubber on recently resurfaced tracks such as Barcelona, Silverstone and Paul Ricard.
The rubber layer of Pirelli's compounds will therefore be 0.4mm thinner at these specific venues, reducing the weight of the cars by a kilo.
Pirelli F1 boss Mario Isola explained the structural change but denied it was being done solely in Mercedes' interest.
"The new asphalt [in Barcelona] is blacker and smoother and producing even more grip. This can lead to overheating," said Isola.
"We would have done it anyway," he insisted, in reference to the modifications.
"With a lot of grip, the lap time is improving a lot. We saw the lap times during the pre-season test was three seconds quicker than last year.
"But the point is that we keep a lot of rubber on the tyre, because with low wear, the tread is there, we are not wearing the tyre. And this means we have high temperatures in the compound.
"So to try to reduce a little bit the temperature we asked for a small reduction in the tread thickness to reduce a little bit the temperature.
"We tested the solution already last year, and in terms of performance or other consequences, they are almost transparent.
"Obviously the reason we stayed on the standard tyre for this year was in normal circumstances you wear the tyre, and if you don’t have enough thickness, you wear the tyre too quickly."
Pirelli invoked a safety argument to justify the in-season change which would normally require a 70 percent agreement from the teams, and the FIA has accepted the specification change.
Needless to say, several outfits are not happy however, believing Pirelli has given in to Mercedes' appeal.
"We have no problems with blisters," a McLaren source said.
Red Bull's Daniel Ricciardo agrees: "Our car is gentler on the tyres than the Mercedes."
An unnamed team boss added: "Why should we change the tyres if Mercedes has a problem?"
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