Pirelli says they won’t know if its new wider tyres have hit their targets, until the first Grand Prix of the 2017 Formula 1 season.

The Italian tyre manufacturer operated an extensive testing programme with Red Bull Racing, Scuderia Ferrari and Mercedes AMG Petronas Formula One Team last year with mule cars, 2015 spec-cars with a wider track modified to simulate the increased downforce that next year’s car will generate. Despite this programme, there are still some question marks on the eve of this season.

The modified cars did not produce the kind of forces that the 2017 challengers are set to bring. Mario Isola, Pirelli’s F1 racing manager reiterates the performance different between the mule cars and the 2017 challengers, as teams have started sending their simulation data to Pirelli.

“They [the mules cars] lacked a bit of performance,” Isola told Motorsport.com. “Although the modified cars aimed to simulate the downforce levels we will find.

“We have not seen the true performance that we will have in 2017. We have seen from the simulations that we have been sent by teams, based on patterns with the new cars, that the performance will be better than those we saw from the mule cars.

“This leads us to still have some question marks on the feedback that will come from the track in the first tests and the first few races of the world championship.”

With uncertainty floating around the new tyres, Isola is keen to stress that the potential problems do not relate to safety. The problem is the degradation and thermal characteristics, something they can only check on track.

“It is not an integrity problem, because our indoor tests are calibrated to the values that have been given to us by the team simulations,” he said. “But these simulations are one thing.

“There will be a completely different performance window in which the teams will arrive in the second half of the season – where we often are on track with high temperatures. Will degradation and overheating be the same as with the simulations? It’s a check that we can only do on track.”