McLaren says 2014 F1 tyre test rain-out will hamper aero teams

Pirelli had brought development sets of next year's products to Interlagos for teams to try out during the Friday sessions.

However, wet weather during the opening day of action meant that proper evaluation of them was not possible.

Sebastian Vettel did manage to get out briefly on a set during the first session, but was not able to go fast enough to allow his team any valuable data gathering.

There are discussions ongoing about teams being given special dispensation to run the tyres in Saturday's final free practice session, but no decision on that has been made yet.

McLaren sporting director Sam Michael said that only proper dry running of the tyres would be of benefit to teams, and it was aerodynamic characteristics rather than handling that teams were most interested in.

"You have two problems testing them [in the damp] in that you have to generate enough lateral force to make the tyres squash - because that is what you are looking for.

"It is the difference in sidewall shape under cornering loads that counts. It is not just a matter of limping around; you need to actually be generating some force.

"But also when you have a lot of spray it fills all the pitot tubes up and then you get a dud reading.

"Lap time and driving around the track is pretty secondary and third order - the most important thing is to get aero data."

When asked what it would mean for teams if they did not get the chance to test the 2014 tyres in Brazil, Michael said: "It just means that it is harder to develop. It is not helpful.

"It would be nice to have it. But if you don't have it, you don't have it - it will be the same as everyone else."