Formula 1's pre-season testing in Barcelona won't be "super-representative" of how Pirelli's new range of tyres will behave in the upcoming campaign, according to Mercedes technical director James Allison.
Pirelli has taken a more aggressive approach this season, highlighted by the addition of the hypersoft to its range.
Teams were able to sample the new tyres at the Abu Dhabi test in November, and could therefore finalise their 2018 designs to suit. They also had to make their compound choices for the first races of this season as early as last December.
The traditionally aggressive Barcelona track surface was replaced in January, which makes the coming week's test a step into the unknown in which data from past years will be less relevant. Rain is also expected to reduce the amount of dry running at the first test.
Said Allison: "It's never easy in Barcelona winter testing to pick up everything that you would wish to about the tyres, because it's winter, and the tyres don't run in the winter on the whole when we're racing.
"And Barcelona is quite an aggressive track on the tyres, it tears them up in the winter, you get a lot of graining.
"This year is going to be particularly interesting because they just resurfaced Barcelona, and it is a lot, lot smoother, and the sort of rubber that would be torn up last year in Barcelona testing could probably survive this year.
"But that doesn't necessarily mean that it's going to be super-representative of the remainder of the year.
"It's going to be a challenge, but our constraints are no different to anybody else's so we just need to operate as efficiently as we can and get the maximum amount of experience in the eight days that we have available to us."
Allison believes teams got enough information from the Abu Dhabi tyre test to put them on an equal footing.
"We would have had as much chance as everyone else to have learned everything that we needed to know," he said.
"But of course it's one track, one test, at the end of season on a circuit that's very kind to tyres, and then having to on the back of that extrapolate what you need for the first bit of the racing season, where you have to choose your tyres blind - well, not blind, informed by the Abu Dhabi test.
"So we would like to have been testing all the time and learning over and over these things.
"It's a level playing field, our team had a good test, we felt we had a programme that allowed us to learn as much as we could in that time.
"We hope that we've made our judgements correctly about tyre selection for the opening races before we learn for real how the thing performs."