Pirelli says that some teams have purposefully "exaggerated" downforce values as the F1 supplier sets its tyre operating guidelines before Grands Prix.
In Barcelona last week, before Friday's free practice, the Italian manufacturer reversed its tendency to allow lower tyre pressures, and Germany's Auto Motor und Sport has a theory as to why that happened.
The report contends that Mercedes has struggled on lower tyre pressures in 2017, after utterly dominating in previous years with higher pressures.
Then, ahead of the Spanish Grand Prix, Pirelli increased the mandatory pressure guidelines after analysing downforce data provided by the various teams.
"The suspicion in the paddock is that Pirelli is deliberately being fed excessively high downforce data in order to keep tyre pressures high," wrote correspondent Michael Schmidt.
"It is said to be always the same two teams which deliver the wrong data."
Pirelli's Mario Isola downplayed the allegations however.
"It is true that some of the downforce values prove in reality to have been exaggerated.
"But such a policy would have little effect, because we can always change the pressures if we feel it is safe to do so."