Sweden : BFGoodrich - PreviewThis year marks BFGoodrich's second visit to the Swedish Rally after the g-Force Ice took Ford's Marcus Grönholm to victory in Karlstad in 2006.
This year, the Finn will be hunting for a fifth personal success on one of the calendar's
most spectacular shows which sees the WRC cars reach speeds of up to 200kph on sheet ice.
This year again, the stud-spangled g-Force Ice promises to take front stage. Ice-cool drivers, half-frozen spectators and cars dancing on sheet ice, brushing snow banks and crossing dark forests at vertiginous speeds with the occasional elk looking imperturbably on…
These are the cliché images of the Swedish Rally, yet the true stars of the show are the tiny tungsten tips inserted in the tyres which strike the ground 17 times every second at 120kph to provide the necessary traction and grip to keep the cars on the icy lanes.
Each g-Force Ice bristles with 384 tungsten studs. But metal and rubber have radically different properties and successful bonding the two is dependent on the quality of gluing technique. For this particular job, BFGoodrich calls on the services of a Swedish subcontractor to insert and glue the studs one-by-one in the orifices of the tread blocks.
The g-Force Ice tyres are made in France before being transported to Sweden where the gluing process takes place.
Preparing each g-Force Ice tyre demands approximately one hour's work. The studs used for the Swedish Rally must comply with strict FIA regulations which specify a maximum length (20mm), a maximum weight (4g) and other key dimensions.
However, the proportion of the stud that protrudes from the tyre can be modified as a function of both the conditions (snow, pure ice, frozen dirt) and the type of ice. There are effectively numerous different types of ice, just as there are different types of sand on the Dakar.
Depending on whether the ice is very cold (-20°C), simply cold (-5°C) or thawing (0°C), the amount of grip available can be very different. To see for yourself, try taking an ice cube from a freezer. To begin with it sticks to the fingers but after a few minutes it becomes so slippery that it is difficult to keep a hold of it. BFGoodrich's technicians will consequently use the information supplied by their route observers and the weathermen to help the drivers choose their tyres.
In 2006, Marcus Grönholm paved the way for his win by choosing the 'long stud' option on Day 2.
