The Formula One teams and Pirelli take a step into the unknown this weekend with the inaugural United States Grand Prix at the Circuit of the Americas: a newly-built track that has never been raced on before.
The Italian firm is bringing the P Zero Silver hard and P Zero White medium tyres: a reasonably conservative compound choice for a circuit where there are still a number of unknown factors when it comes to tyre performance. The teams will be given an extra set of the hard tyre for Friday's two free practice sessions in order to help them learn the all-new track.
One sure thing is that the Texas circuit will be fast and challenging, with warm ambient temperatures adding to the mechanical demands placed on the tyres. The 5.515-kilometre track features varying elevations that alternate slower and more technical sections with other areas that are very quick. Initial information suggests that the track surface will be quite smooth.
The opening sector of the lap is particularly demanding, with a uniquely profiled hairpin turn one and then a rapid sequence of direction changes from turns four through to six: reminiscent of Silverstone or Spa. This puts a lot of energy through the tyre structure, particularly the outside tyre that has to withstand the majority of the cornering forces. Traction is also a vital aspect of tyre performance in America in order to find optimal grip coming out of the slower corners.
With no data from previous years to fall back on, Pirelli has used advanced simulation technology to predict how the tyres might behave on the Austin circuit. The teams will also use similar data when it comes to formulating some initial ideas about race strategy; however the information gained from free practice will be even more vital than usual. Teams will be aiming to collect as much tyre data as possible on both full and empty fuel tanks and the extra set of hard tyres should enable them to maximise their running.
Paul Hembery: "Austin is one of just three new tracks for us in Formula One competition this year, alongside Bahrain - which we've tested at previously - and Hockenheim, where we previously raced in GP3. So in many ways America will be the biggest challenge for us of the year, but stepping into the unknown is a situation that we are used to: last season the majority of tracks were completely new to us. We've chosen the hard and the medium compounds as we think it will be quite a demanding track, based on the asphalt samples and simulation data we have gathered. Naturally we've leaned towards a slightly more conservative choice in order to cover every possibility at a brand new circuit, but the tyre choice in Abu Dhabi was also conservative and yet we saw one of the most exciting races of the year. We're all absolutely delighted to be returning to America with Formula One: it's a crucial market for us as well as being the home of many of the most enthusiastic fans out there. We've felt a huge buzz about this race, and with the championship so finely poised it couldn't come at a better time."
As Austin is a brand new circuit, the surface is likely to be 'green' and slippery, with a high degree of track evolution over the weekend. A totally new track often has a thin film of greasy oil on the surface, which is released by the asphalt as it settles into place. The race length will be 56 laps.
Turn 11 is also particularly demanding in Texas as the driver starts braking heavily with the car already turning, creating an uneven distribution of forces across the tyres. Good grip from the compound is essential for an effective turn-in.
The cars are likely to run with low gearing and medium downforce, with the set-up not expected to be dissimilar to that of Istanbul Park in Turkey.
The weather can be uncertain in Texas at this time of year, with a 31% chance of rain on any given day on average. The month of November is characterised by rapidly falling daily high temperatures, with daily highs decreasing from 25 degrees C to 19 degrees C over the course of the month, exceeding 29 degrees C or dropping below 13 degrees C only one day in 10.