Four-time world rally champion Juha Kankkunen set a world record for driving on ice recently, hitting 199 mph across the Gulf of Bothnia near Oula in a Bentley Continental GT equipped with studded Nokian Hakkapeliitta winter tires.
The backers of the speed record attempt adhered to Guinness Book of World Records rules, which among other things required the car to be equipped with tires approved for road traffic in the country where the attempt took place. The car ran on Hakkapeliitta Sport Utility 5 tires, which are designed and developed for city sport-utility vehicles, according to Nokian Tyres P.L.C.
Tire choice was considered critical for this record attempt, Nokian said, because ``as the air resistance increases, more traction is needed in order to pick up speed. The tires are under immense pressure at these high speeds, and their diameter can increase by 15 to 20 mm (up to 3/4 inch).''
In order to achieve a steady driving speed of 199 mph, a traction force of approximately 3,000 Newtons is required, Nokian said.
``For the vehicle to accelerate, you need even more force,'' said Nokian Tyres Development Manager Kai Hauvala. ``The tires must be able to transfer this force into the ice, or the tire will slip and the vehicle will not accelerate as hoped.''
In addition, Nokian said, when a vehicle moves at a speed of 199 mph, a stud weighing 1 gram creates a pulling force equivalent to approximately 2.2 kg (4.8 lbs). The vehicle covers nearly 300 feet in one second, and each stud hits the ice more than 40 times a second.