Hanover / Arvidsjaur, February 2006. The Semperit Speed-Grip will be on the market from this autumn, and in initial driving tests the tyre demonstrated very good road holding on icy or snow-covered roads. This is down to the innovative network sipe structure, which means high grip during braking and starting off, combined with safe lateral guidance on typical winter roads. The tread pattern was also designed to provide dynamic handling characteristics on dry roads and good water dispersion when driving in the rain.

Traditionally, the main attraction of Semperit winter tyres has been their safe driving characteristics on snow-covered and icy roads. Developed specifically for road conditions in Alpine regions, they also ensure reliable, safe winter driving performance in the lowlands. In the new Speed-Grip the designers have created a dedicated winter tyre that can not only safely handle fast motorway driving at speeds up to 240 km/h (150 mph), but that also offers extra grip in snow and ice. Traction in snow has been improved by three per cent compared with the tyre's predecessor, whilst lateral guidance is four per cent better. The new compound has enabled braking distances on wet roads to be reduced by four per cent, with aquaplaning protection enhanced by a full six per cent.

Network sipes mean greater grip in snow and ice

The innovative sipe technology used on the Semperit Speed-Grip provides extra grip when starting off and braking, combined with high lateral guidance in snow. "The network sipe structure, where the individual fine grooves in the tread lugs form inclined rectangles, allows individual sipes greater flexibility" explains Akif Celik, developer of the new Speed-Grip. "Under load they form a multiplicity of effective edges that interlock with the ground, thereby ensuring highly positive grip." As the sipes are arranged both longitudinally and laterally, they also have this beneficial effect when a tyre enters a bend and when actually travelling through the bend. Compared with traditional wave-shaped sipes, this technology means substantially greater interlocking with the ground - and thus improved road holding.

Not only do the new network sipes offer advantages when driving in snow, they are also superior to conventional technology on icy roads. The reason for this is that as the sipes are interlinked in the tread lug, the film of water created when braking and accelerating on ice can be channelled away more quickly to the tread grooves. On ice the sipes work like windscreen wipers, dispersing the film of water that would otherwise reduce grip. This means better contact with the ice on the road and subsequently better grip, which helps reduce braking distances.

More tread lugs for better grip

To boost grip even further, the new Speed-Grip has a large number of tread lugs in the tyre shoulder. Under load, these tread lugs form a multiplicity of edges that can interlock with the snow, thereby creating additional grip. A further positive effect of this design is that numerous grooves are formed which can quickly channel water out of the ground contact patch when driving in the rain. The directional orientation of the tread pattern further reduces the risk of aquaplaning.

High tread stiffness - good for dry roads

A continuous central rib in the tread pattern enhances the Alpine-proven driving characteristics of the new Speed-Grip on dry roads. The longitudinal stiffness created in this way ensures positive grip on asphalt roads and thus shorter braking distances. Additional sturdy tread lugs in the centre of the tyre provide high lateral stiffness, giving a precise steering response and high track stability. To reduce tread lug movement during cornering, the network sipes in the tyre shoulder are embedded in sturdy tread sections (so-called 'supporting walls'). This enabled the tyre developers to achieve precise handling on dry roads, without reducing the impact of the network sipes when driving in the snow.

As the sipe density is adapted to the individual tread lugs, Semperit's new winter tyre has an even tread stiffness across the full tyre width and circumference. This ensures even tyre wear and thus high mileage performance - an important factor for motorists looking to combine high driving safety in wintry conditions with economy.

Semperit is a tyre brand of Continental AG. The Continental Corporation is a leading supplier of tyres, brake systems, chassis components, vehicle electronics and technical elastomers. In 2004 the corporation realised sales of EUR12.6 billion. At present it has a worldwide workforce of more than 81,000.