TÜV SÜD advises drivers to buy winter tyres now

TÜV SÜD advises drivers to buy winter tyres now

Like summer tyres not so long ago, the prices of winter tyres are now soaring as the already high price of natural rubber continues to rise. Enormous demand by tyre manufacturers, particularly manufacturers from the Far East, is further fuelling this trend. Against this backdrop, TÜV SÜD experts recommend that motorists buy new winter tyres now, pointing out that the use of winter tyres is required by law. TÜV SÜD also advises motorists on what to watch out for when buying new tyres to put the brakes on rising mobility costs.

The price rises for natural rubber, a raw material in tyre production, are primarily caused by flooding in rubber-growing countries such as Malaysia and Indonesia last year and by soaring demand, primarily in China and India. These countries already need one-third of the global rubber production. After doubling in 2010, rubber prices leapt further by almost 50 per cent at the start of this year, reported the German Tyre Dealer Association (BRV). To make matters worse, the price of crude oil – another important constituent of tyres – is also steadily increasing. What does this mean for drivers? "Buying tyres early will save money on their purchase. And motorists who also look carefully at rolling resistance will save fuel and help the environment", comments Michael Staude, tyre expert at TÜV SÜD Automotive and Chairman of the European commission for the standardization of tyre rolling resistance laboratories.

It's all in the rubber: Winter tyres offer distinct safety advantages in the cold season. In wintry conditions, summer tyres provide significantly less grip, because the rubber compounds in summer tyres start to lose elasticity and begin to harden at temperatures of slightly above zero. The rubber used in winter tyres is generally softer, containing higher levels of natural rubber or silica, so that the tyres are able to adapt better to the road contours. And winter tyres perform particularly well on snow and slush. "On a road covered by snow and ice, the braking distance may more than double with summer tyres", explains Michael Staude. "Apart from these undisputable advantages, the use of winter tyres in wintry conditions was made mandatory in Germany last year", says Staude.

The driver's preferences and habits are crucial: Before making a purchase, motorists should reflect on how they use their cars in winter. For ski enthusiasts travelling to the mountains each weekend, for instance, the tyres' performance on ice and snow has top priority, while commuters driving mainly on motorways place more emphasis on durability and wet grip. Once drivers have decided on how they use their tyres during winter, the results of winter-tyre tests will provide a good overview.

Tyre markings are important: The oldest and most widespread marking identifying cold-weather tyres is M & S or M+S, which stands for "mud and snow". However, there are virtually no binding requirements regarding the performance of mud and snow tyres on winter roads. In the USA, for example, even summer tyres may come with the M&S symbol on the sidewall. In Europe, this has also become common practice for 'all-terrain tyres' and SUV tyres. According to TÜV SÜD, these tyres offer very restricted performance on wintry roads. The Americans have learned their lessons from the inadequacy of the M & S symbol and introduced the snowflake symbol – a snowflake in a stylized mountain range – which guarantees reliable winter performance. As the tyres of renowned European manufacturers clearly outperform these requirements, they rightly bear this symbol on their sidewalls. "The mountain/snowflake symbol on a brand-name tyre provides good guidance for tyre purchasing", notes Staude.

All-season tyres? Using the same set of tyres all year round is an appealing idea. However, all-season tyres are always a compromise. In TÜV SÜD's opinion, this type of tyre is only suitable for driving in flat and relatively snow-free regions without major gradients. From a financial standpoint, all-season tyres also fail to make the gold standard, as they often wear faster and have a higher rolling resistance than tyres that are changed to suit the season. However, all-season tyres are marked with the M & S symbol and comply with the currently applicable legal requirements for "suitable tyres".

Sliding into trouble with summer tyres: In pubs and internet forums, views are sometimes bandied around that summer tyres are the better choice in some wintry road conditions. Icy roads are one example particularly frequently mentioned in this context. "This is dangerous nonsense", warns Staude. "The braking distances of summer tyres on ice-covered roads, let alone on snow-covered roads, are significantly longer than those of winter tyres. Additionally, cars fitted with summer tyres are far more critical to handle and perform less predictably on icy and snow-covered roads."

Think of the environment: Is cutting CO2 emissions out of the question with winter tyres? Is good grip on ice and snow intrinsically irreconcilable with energy saving? "No", replies Staude firmly. "Driving performance and low rolling resistance have played a major role in the design of winter tyres for years."

The results of tyre tests confirm this statement: where rolling resistance is concerned, cold-weather tyres need not fear comparison with summer tyres. To ensure further improvement of these characteristics, the law will gradually introduce stricter limits in tyre production from November 2012 onwards. In addition, in the future tyres will come with labels which provide consumers with all the important information at a glance. Parameters will comprise wet grip, consumption, rolling resistance and noise development. "Tyre purchasers should also ask the tyre seller about the tyre's environmental performance", advises Staude. Energy efficiency does not affect safety: "All products of the well-known major tyre manufacturers represent a good compromise between a host of criteria, including snow grip, durability, wet and dry performance and rolling resistance", explains the TÜV SÜD expert.

 No worries over higher fuel consumption: A persistent prejudice against winter tyres concerns their allegedly higher fuel consumption. "Fuel consumption rises in winter because of the cold temperatures, not because of the tyres", comments Staude. Nowadays, brand-name winter tyres generally offer almost identical rolling resistance to summer tyres. And today, purchasers can even buy winter tyres which deliver especially low fuel consumption. These tyres are identified by markings such as "Green X“, "ECO" or "Saves Fuel".

Size does matter: Motorists preferring to drive on big and wide tyres can continue to do so in winter, thanks to the ranges of products offered by tyre manufacturers. However, Staude recommends practising restraint. As a rule, a slightly smaller tyre size may be the better choice in winter. Motorists who may want to put on snow chains if necessary need to forego very big and wide tyres in any case, otherwise there may be insufficient clearance between the chain and the wheel arch. Further information can generally be found in the car's manual.

Keeping track of tyre tread: Even if the legal limit for minimum tread depth on your winter tyres is the same as for summer tyres, i.e. 1.6 mm, experts and tyre manufacturers agree that the depth of tread on winter tyres should not fall below four millimetres. One of the reasons for this is that with winter tyres – even more than with summer tyres – different rubber compounds are used for the tyre tread and the tyre carcass.  During the vulcanization process these different rubber compounds mix at an intermediate layer. As a result, on a badly worn tyre, the tread thus approaches this intermediate layer of mixed rubber compounds, which no longer offers the desired consistency - and thus the desired performance. Performance also decreases because winter tyres are primarily composed of sipes. "The shorter the sipes, the less flexible they are – which adversely affects grip", explains the tyre expert. People travelling to certain countries must have greater tread depth during winter in any case: in Austria the legal limit is four millimetres, and in Sweden three.

Pace yourself: The times when the maximum speed for cars fitted with winter tyres was 160 km/h have long gone. Today, winter tyres are generally approved for a speed of up to 190 or 210 km/h, and some even for 240 or 270 km/h. In the latter case, motorists may have to lower their sights  regarding winter performance. An important fact to know is that if the maximum speed rating of the tyres is below that of the car, this fact must be pointed out by a sticker in the car's cockpit – otherwise the driver may face a fine.

Pump up the pressure: Tyre pressure is critical for fuel consumption. Reduction in inflation pressure by as little as a few tenths of a bar raises rolling resistance by up to 20 per cent and dramatically slashes safety. EU citizens waste over two billion euros every year by under-inflating their tyres! "0.2 to 0.3 bar over the pressure recommended by the car manufacturer does no harm", advises Staude. However, if the winter tyres are exposed to maximum stress – while driving in the mountains, for example – keeping strictly to the recommended pressure is better. Staude: "At this pressure, the tyre offers optimum performance."

Stress-free changing: Motorists who do not want to wait for weeks for their winter tyres or queue up to have their tyres changed should start looking for the right winter tyres now, advise TÜV SÜD's experts. This applies all the more against the aforementioned background that bottlenecks in the supply of winter tyres and the concomitant price increases must be expected in the coming winter.

"Use our know-how. Shape your future." is the motto of TÜV SÜD at the 2011 International Motor Show IAA  in Frankfurt am Main from 15– 25 September. The central themes of TÜV SÜD's presence at the trade fair in Hall 8, Stand A19 are innovative services for the automotive sector and electromobility. Visit us at the IAA. Further information about TÜV SÜD's activities at the IAA can be found here.

Contact: Frank Volk