Understanding how Pirelli's 2017 tyres will respond has been a "huge challenge" according to McLaren technical chief Tim Goss.
Although Pirelli have conducted thousands of kilometres in testing and provided all teams with equal data, Goss says McLaren are still working out what to expect, but believes they're getting there and is looking forward to pre-season testing to confirm their expectations.
Pirelli's new tyres are wider and are expected to last longer, allowing drivers to push at the limit for the entire race. However Pirelli has had to rely on test data from mule cars provided by Ferrari, Mercedes and Red Bull and that, according to Goss, creates an extra challenge when trying to understand the data provided by Pirelli.
"Understanding what the tyres are actually going to do has been a huge challenge," he told the McLaren website. "Pirelli ran a very intensive test programme during 2016 to develop the new tyres, with the support of three teams.
"They got lots of mileage under their belts throughout 2016, and all that data has been provided to all the other teams. But, from all of that testing, trying to piece together what we think the tyres are going to do in terms of performance, degradation, thermal stability etc, that's still quite challenging.
"And there's a couple of reasons for that: even nowadays, it's still quite difficult to understand tyre behaviour – even if you go track-testing. Additionally, the 2016 mule cars won't behave in the same way as the 2017 cars – so what we're trying to do is identify which areas of performance are attached to the tyre and which to the mule car. That's a major challenge."
No team will know if they've got their calculations correct until pre-season testing, and that's when the learning begins according to Goss.
"We're pretty close to knowing what we're going to get from the tyres, but really understanding how they'll sync with the new regulations will be quite a challenge. In pre-season testing, we will learn a lot."