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EQUIPMENT

Tires

POLAR RINGS NOKIA

Nokian Tires is the northernmost tire manufacturer in the world. Here, in Lapland, near the town of Ivalo, which is 300 kilometers north of the Arctic Circle, there is a testing ground for winter tires.

Sergey MISHIN

The working season of the winter training ground is from November to May. There is only snow and ice underfoot, so there is no need to equip expensive special test roads. Nature took care of everything. The tracks are laid along the frozen surface of three lakes and a country road that borders the landfill. From man-made - only an office with a living room, a small garage and a gas station.

The longest lake was adapted for evaluating tires in acceleration and braking on ice (three parallel kilometer stripes of 20 meters each). Here a small closed eight-hundred-meter track was sheltered. On another lake, an ice ring with a diameter of 300 meters is marked, where the lateral coupling properties of tires on ice are determined, and a 2300 m high-speed road. Another ice route - for special shows and the "northern driving school" - is laid on the third lake.

Along the perimeter of the landfill in the circumpolar forest there is a clearing with a snowy 15-kilometer road, where there are many turns, small descents and ascents. Here they evaluate the behavior of a car shod in test tires in the snow. In addition, there is a special wide strip with a length of 500 meters, a mountain road with serpentines, laid along the slope of the coastal hills using the terrain - slopes up to 20%.

Half a year to live in the middle of winter, away from civilization, albeit with all conveniences, is not to everyone's liking, therefore, the landfill staff is divided into shifts and works on a rotational basis. There are four to five highly qualified test drivers and a janitor on duty.

The former, jacks of all trades, perform what is connected with the tests (measurements on complex electronic equipment, information analysis, expert assessments). They do not shy away from rough work - changing a car, mounting tires, balancing wheels - everything rests on them. The Janitor cleans all test and access roads (of course, not with a manual broom).

Work begins with measurements of the main tire parameters. They are carried out on a special car-stand with a third suspension axle, and wheels with tested tires are put on it (photo at the top right). With special clamping devices, they can be pressed to the road with one or another force, set the desired axis rotation speed, and turn the wheels to any angle. Objective indicators of longitudinal and lateral adhesion on snow and ice are measured and recorded in electronic memory.

After that, the tires are put on a regular car for testing: measuring on the road and assessing behavior in various modes in various winter conditions.

To determine the coupling properties of tires, cars are accelerated with an intensive slip and measure the speed of climb from 5 to 25 km / h. The braking distance, on the contrary, is measured from 25 to 5 km / h with the front wheels locked. At the same time, the rear brakes are disabled to remove possible lateral withdrawals during intensive braking. The lateral grip of the tires is estimated by the maximum speed achieved on the ice circle.

But numbers are a dry thing, though objective, but how to evaluate the advantages of tires in the language of sensations? Great importance is attached here to the expert assessment of the car’s behavior on the road in various driving modes (acceleration, braking, cornering) and tire comfort (noise, smoothness and vibration damping on bumps). If required - in comparison with competitors. At the same time, they put down grades according to the Finnish school system familiar to experts: the lowest - 4, the highest - 10.