From tomorrow, Bahrain's Sakhir circuit hosts the official test session that kick starts the 2025 Formula 1 season.

It's the only opportunity to see the ten new cars out on track together before the lights go green at Melbourne on 14 March to signal the start of free practice for the Australian Grand Prix, the opening round of the calendar.

The three days provide the teams with a total of 24 hours of track time, from 10:00 to 14:00 and from 15:00 to 19:00 (local time), providing some initial indications of what to expect this season.

The test will also be an opportunity to see this year's entire Pirelli range of homologated dry-weather tyres. Their construction has been slightly modified to better suit the increased aerodynamic loads that they will be subjected to by the latest version of this generation of cars.

Six compounds are available and they can be identified as follows: C1 with the words Pirelli and P Zero in white, but with no bands; C2 with the words and bands in white; C3 with the words in yellow, with no bands; C4 with the words and bands in yellow; C5 with the words in red with no bands; C6 with words and bands in red. The intermediate and extreme wet tyres maintain their usual colours of green and blue respectively.

This coming season marks the debut of the C6, which in line with the naming system adopted by Pirelli for several years now, places it at the softest end of the range. It will be suited to Grands Prix run on street circuits and at other tracks where their characteristics mean tyres are subjected to low energy levels.

As for the other compounds, the C1 is again the hardest, and remains very similar to the 2024 version, while the C2 is now closer to the C3, the latter being the most versatile in terms of balance and degradation is substantially the same as the version homologated for the previous two seasons; work on the C4 has centred on reducing the possibility of graining appearing on the tread surface and of degradation, as is also the case for the C5, with the aim of increasing its ability to work in race conditions.

For the Sakhir test, each team can select up to 35 sets of tyres, of which 30 can be used over the three days. Studying the choices made by the teams throws up some interesting indications.

This track has always been very hard on tyres, which is why the three hardest compounds are usually chosen for the Bahrain Grand Prix. The C3 is by far the most popular choice for the test, partly because it will be the most used tyre over the course of the season, as was the case in 2024.

However, this year, with six compounds available, it could be absent from some Grands Prix. Mercedes is the team opting to use the most sets of C3 (27), with Williams at the other extreme with just 15 sets of this compound. These teams swap places when it comes to the C2: 12 sets for Carlos Sainz and Alexander Albon and just two for George Russell and Kimi Antonelli.

Ferrari and Williams have opted to run all six compounds, which means they only have one set of C5 and C6 each, while Aston Martin and Alpine have limited their choice to just the three hardest compounds. Finally, it should be noted that Aston Martin and Haas are prepared for every meteorological eventuality, the former including three sets of intermediates in their allocation, with the American team going for one of intermediates and one of extreme wets. At the moment, according to the FIA's official forecaster, Meteo France, there is no possibility of rain over the three days.