Did you know that on each rally, the Subaru World Rally Team can have up to 150 wheels and tyres available for its three cars?

Petter, Chris and Xevi can all choose between five types of the BFGoodrich g-Force tyre before each rally.

Available from studded ice tyres to cut slicks (where a minimum of 17 per cent has to be treaded), each type is available in different compounds, the overall range from super-soft 0 compound to the hardest compound 9 .

The BF Goodrich g-Force Profiler tyre is used on asphalt rallies, its low sidewalls offering improved stiffness and large contact patch improved grip on smooth and dry surface.

Its brother, the g-Force Profiler Humid, is the weapon of choice for wet asphalt. The g-Force Winter offers a similar tyre with the addition of metal studs for extra grip on ice. This tyre is used exclusively on Rally Monte Carlo.

The g-Force Ice is used only on the Swedish rally, its tread comprising of long or short metal studs to give maximum grip on the wintry stages. Finally, the g-Force Gravel is available in low-, medium- and hard-wearing construction, with a relatively compact tread to maximise grip while cutting through loose gravel surface.

The drivers have to nominate their chosen tyres by four weeks in advance of long haul rallies or four days in the case of European events. The combination of tyres used for each rally will depend on the type of surface and the predicted weather, testing the team's forecasting accuracy.

The process of cutting is common with rally tyres, involving removing rubber to enlarge existing or create new tread grooves.

Enlarging cuts can make the tyre more suited to rough surfaces, improving traction on loose material. Extending cuts to the wall of the tyre makes it better at dispersing water, sluicing it away from the contact patch.

BFGoodrich technicians will fit their tyres to wheels supplied by the team by the Wednesday morning before a rally.

A specially-designed anti-deflation mousse is used inside each tyre to prevent punctures. Shaped like a flexible donut that lines the inside of the tyre, it is compressed when the tyre is inflated. A cut or puncture reduces the pressure inside the tyre and allows the foam to expand, sealing the leak immediately.

When the team receive the fitted wheels and tyres, they will be inflated to a pressure of 2bar and loaded in batches into mobile air-heater units. Not dissimilar to a pizza oven, the units will be warmed to 55 degrees Celsius for an hour for a strong seal between metal and rubber.

Once heated, they undergo a process of being inflated to 4bar and deflated fully four times over to remove any moisture inside each tyre. They are then inflated with carbon dioxide to a pressure of 2bar, ready for use. Carbon dioxide is used as it is more stable under pressure and high temperatures.

Tyre pressures are set at around 1.8bar, or 30psi, so having the tyres pre-inflated means it is considerably faster for the engineers to deflate them to the necessary pressure than it is to inflate them.

As service durations are counted to the second and tyre choices made last minute, every last drop counts.