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Fri May 11 08:38 am 2012 in category Product news
Unique truck tyre winter test event in Ivalo, Lapland

Safe winter driving requires good winter tyres on both the truck and trailer



By law the minimum tread depth for heavy-duty vehicles' winter tyres is 1.6 mm, which is far too low. Also, it is important to pay attention to all of the vehicle combination’s tyres. Often, only the truck is equipped with new tyres in the autumn. Good tyres raise the maneuverability of the vehicle combination to a whole new level in comparison with worn tyres and give the driver much more control over braking, acceleration and cornering.

These factors, among others, became clearly evident in the heavy-duty winter test arranged by Nokian Tyres, in co-operation with VR Transpoint, the University of Oulu, Liikenneturva, Oulu Vocational College and Kainuu Region Vocational College in Ivalo in March.

The clear difference between the test results of new winter tyres versus worn ones took the numerous journalists and experts by surprise. The tests were driven using two identical vehicle combinations. In the first vehicle combination, the truck was equipped with new Nokian Hakkapeliitta Truck F front winter tyres and Nokian Hakkapeliitta Truck E winter traction tyres, and the remaining tyres were new, so-called All Season tyres. The other vehicle combination had worn All Season tyres with a tread depth of about 5 mm all around.

Braking distance up to 30% longer with worn tyres



The tested maneuvers comprised ABS braking from various speeds, the double lane-change test and an acceleration test. The test surface consisted of hardened snow and ice. The vehicles were equipped with test sensors that measured such features as acceleration in multiple directions and yaw velocity. The total weight of each vehicle was approximately 43 tonnes. The variations between the results gained with new and worn tyres were very clear.

"In ABS braking, the braking distance with worn tyres was, on average, 30 per cent longer. From an initial speed of 70km/h, the residual speed at the moment of impact was about 35 km/h. In the acceleration test spanning 70 metres, the vehicle combination with worn tyres was still one vehicle combination length behind at the time that the one equipped with new tyres had already reached the destination," says truck tyres' R&D Manager Teppo Siltanen, summing up the test results.

No surprises with new winter tyres



The double lane-change test highlighted equally clear differences between the two vehicles. The truck with new tyres did not understeer and it featured less lateral movement on the drive axle, and the dolly and trailer followed the truck consistently. The truck with worn tyres, on the other hand, understeered heavily and its rear end slid laterally. The dolly pushed against the truck, and it was difficult to return the vehicle combination back to the lane.

This test clearly points out how important it is to pay attention to vehicle combination’s tyres in the winter. It is quite common to only equip the truck with new tyres in the autumn. For maximal safety, it is essential to choose tyres with an open tread design and the M+S marking. The depth of the tread pattern is significant especially when driving on snow or slush. Strong siping further enhances grip.

Minimum tread depth 5 mm



Nokian Tyres believes that the minimum legal winter tyre tread depth of 1.6 mm is much too low.

"The truck's tyres should have at least 5 mm of tread depth, and the trailer tyres' tread depth should be no less than 3 mm. For example, in Sweden, Norway and Germany, the use of tyres suitable for winter conditions is required by law. The Swedish law stipulates that the minimum tread depth of the truck's tyres between 1 December and 31 March is 5 mm. This should also be the minimum tread depth requirement in Finland," Siltanen suggests.

Good tyres increase the maneuverability of the vehicle combination to a whole new level in comparison with worn tyres and give the driver much more control over braking, acceleration and cornering. Global warming has added more variation to winter weathers and conditions. It is always important to maintain a suitable speed for the given situation, particularly with regard to the braking distance, and the corner speed should also always be kept at a safe level.

Nokian Tyres' truck tyre winter test event March 2012



Key results:

  • In ABS braking, the braking distance with worn tyres was, on average, 30 per cent longer. From an initial speed of 70km/h, the residual speed at the moment of impact was about 35 km/h.
  • In the acceleration test spanning 70 metres, the vehicle with worn tyres was one vehicle combination length behind at the time when the one equipped with new tyres had already reached the destination.
  • The truck with new tyres did not understeer and it featured less lateral movement on the drive axle and the dolly and trailer followed the truck consistently.
  • The truck with worn tyres, on the other hand, understeered heavily and its rear end slid laterally. The dolly pushed against the truck, and it was difficult to return the vehicle combination back to the lane.
  • It is important to pay attention to all of the vehicle combination’s winter tyres, not only those of the truck.
  • Good tyres raise the maneuverability of the vehicle combination to a whole new level in comparison with worn tyres and give the driver much more control over braking, acceleration and cornering.

Watch the video: http://youtu.be/ewoFrzlnWr4

Further information about the topic:

Prepare for the winter, don't let it surprise you
https://www.nokiantyres.com/be-prepared

Further information:

Nokian Tyres plc
Teppo Siltanen
R&D Manager/truck tyres
tel. +358 10 401 7709
teppo.siltanen(at)nokiantyres.com

Nokian truck tyres: Safe and economical driving in demanding professional tasks



Nokian truck and bus tyres are designed for demanding professional use in varying conditions with the aim of ensuring safe driving in all weather and road conditions. In our own test centres in Ivalo, Lapland, and in Nokia we test extreme driving situations in all seasons. Further development of the tyres involves millions of kilometers of driving in various usage environments, and in all kinds of weather conditions. Close co-operation with transport operators and haulage companies provides us with valuable user experiences to support our product development. The aim of our versatile testing is to offer the safest and most economical tyres for professional drivers. Our solid expertise relies on extensive traditions. We developed the world's first winter tyre for heavy-duty vehicle drivers in 1934.