ERJ staff report (LMH)
Nokian, Finland - Nokian Tyres has reported the results of what it calls a â€œuniqueâ€ truck tyre winter test event in Ivalo, Lapland.
Nokian, which organised the event, claims that it found that the minimum tread depth for heavy-duty vehicles' winter tyres (1.6 mm in Finland) is far too low. It noted also that good tyres raise the maneuverability of the vehicle combination to â€œa whole new levelâ€ in comparison with worn tyres and give the driver much more control over braking, acceleration and cornering.
The â€œclear differenceâ€ between the test results of new winter tyres versus worn ones took the numerous journalists and experts by surprise, according to Nokian. The tests were driven using two identical vehicle combinations.
The tested manoeuvres included ABS braking from various speeds, the double lane-change test and an acceleration test, on a surface of hardened snow and ice. The total weight of each vehicle was approximately 43 tonnes.
"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,â€ said Nokian truck tyres R&D manager Teppo Siltanen.
He added, â€œIn 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.â€
Nokian said it 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,â€ Siltanen suggested.
Nokian also noted that the truck with new tyres did not understeer while the truck with worn tyres understeered heavily and its rear end slid laterally.
This is an external link and should open in a new window. If the window does not appear, please check your pop-up blocking software. ERJ is not responsible for the content of external sites.
Press release from Nokian Tyres