The season for summer tyres has started for good. Most drivers have already replaced the tyres, but some are still lingering, wondering if a changeable weather would not surprise them with snow and frosty mornings. But can you imagine that you do not need to wait for the right moment to change the tyres and just drive winter ones all year long? And how much time and money you can save this way! Sounds tempting, doesn't it? But are winter tyres suitable for summer driving at all? What are the risks and does it pay off at all? Read the article and find out more.
Many external factors may affect the technical properties of tyres.
Winter tyres in summer – regulations
Specialists recommend replacing winter tyres with new ones when the tread is less than 4 mm deep which is about half the depth of the tread in new tyres. Many drivers may find this surprising because the depth required by regulations is only 1.6 mm. Can we get a fine for driving winter tyres in the summer? It is quite likely, if the wheels reach the prescribed limit; moreover, vehicle’s registration document may be revoked. In such a situation, the traffic police may consider the vehicle unroadworthy.
For the sake of time and money, however, many people begin to wonder whether to "drive winter tyres to capacity” even in summer, instead of discarding them after the season.
Summer vs. winter tyres
According to experts from the German organization ADAC, winter tyres lose their full performance and properties with the wear of the tread. They do not provide such excellent grip on snow anymore and do not facilitate starting, stopping or track control as effectively as tyres with new tread. The fact is, however, that winter tyres with less than 4 mm tread still have better performance than worn summer tyres. Therefore, it might seem that driving on winter tyres could make ecological and economic sense, but this is not entirely true. However, before we consider all advantages and drawbacks of such a solution, we must be aware of the differences in tyres designed for particular season. Worn-out winter or summer tyres may be problematic in recycling, but we have a couple of ideas on how to deal with this issue and give second life to old tyres.
We asked a specialist from Continental company about key differences between winter and summer tyres:
Summer vs. winter tyres - what is the difference?
Summer tyres differ from winter tyres primarily in the tread material, shape and notches carved on the tread, the so-called sipes. Let's start with a rubber compound which is of paramount importance when driving in winter on clear roads or roads covered with hard-packed snow.
Tread material in winter tyres is specially designed to remain flexible even at low temperatures ensuring optimum surface grip; contrary to the summer tyre material which starts to harden at temperatures below 7°C, thus reducing comfort and safety while driving.
Another important and distinctive feature of winter tyres is the tread pattern and sipes which provide optimal grip and traction control on fresh and loose snow. A wide and deep tread in winter tyres enables snow accumulation, and thus providing additional grip on snowy roads (the best grip is on snow-to-snow touchpoint).
In addition, these treads allow quicker drainage of water, melted snow or slush, thus ensuring better tyre-road contact. A characteristic element of winter tyres are sipes - a system of numerous tread notches providing a greater number of gripping edges, and increasing the tread elasticity. As a result, the tyre has better grip on snow and on a thin layer of water (a water film) that occurs between the tread and the icy surface as a result of the heat generated by the tyre.
In conclusion, summer and winter tyres are two different things. We would like to encourage you to change your tyres seasonally, because only tyres matched to the season will ensure maximum safety on the road in all conditions.
Head of the Technical Department at Continental
Actually, already at this point it can be concluded that seasonal tyre change seems worthwhile. Let's proceed a step further and ask the expert another question.
Winter tyres - how do they perform in the summer?
How do winter tyres perform in the summer?
Winter tyres - as the very name suggests - are designed for driving at lower temperatures than those prevailing in summer season (threshold 7°C). Winter tyre material becomes too soft and elastic in summer conditions, therefore, the tread would be unnaturally deformed and could easier lose the grip on the road especially when accelerating, braking, or cornering. As a consequence, braking on winter tyres will take longer, they are more likely to lose traction while accelerating and on curves (the "tyre floating" phenomenon). This effect will aggravate as the speed increases, and given good visibility and better weather conditions in the summer, drivers tend to step on the gas pedal. Winter tyres would also fail on rainy days. It is worth adding that winter tyres will wear out faster and will produce louder noise while driving due to their softer rubber material and more aggressive tread pattern.
To sum up, driving on winter tyres in the summer has no economic justification; moreover, it significantly reduces driving comfort and safety both for the driver and other road users.
Head of the Technical Department at Continental
It is safe to use winter tyres in the summer?
One of the major hazards related with driving on winter tyres in the summer is the extended stopping distance. Why? Because even the most attentive and careful driver cannot avoid unexpected situations that may happen on the road. According to ADAC, the stopping distance at 100 km/h on winter tyres in the summer is sometimes 16 m longer than the same on summer tyres. Thus, at the point where a vehicle with summer tyres would stop, the speed on "winter" tyres is still sufficient to kill a pedestrian or to damage the car up ahead.
Winter tyres in the summer - at high temperature and with a greater load
Differences in driveability between winter and summer tyres are not particularly noticeable on cold days. This changes with higher temperature and greater vehicle load. On warm days, especially on a dry road surface warmed up by the sun or with fully-loaded car, the stability and grip of "winter tyres" deteriorate significantly. This may be experienced mainly on curves - the car begins to "float", which resembles driving on an icy road.
Another major disadvantage of "winter tyres" is a greater tread wear and tear due to their softer rubber material which provides better driveability at low temperatures, but faster "wear" on hot surfaces. Soft rubber which performs exceptionally well in cold weather tends to stick to heated asphalt and generates more noise, thus lowering the driving comfort. Rolling resistance is noticeably higher which results in higher fuel consumption. In addition, winter tyres are more susceptible to mechanical damage in the summer.
Winter or all-season tyres?
All-season tyres are a solution preferred by drivers who do not want to buy two sets of tyres and want to economise on their change at a car service. All-season tyres are extremely versatile - they combine the advantages of summer and winter ones. It is worth noting, however, that their performance is somewhat compromised in comparison with tyres dedicated to specific seasons. All-season tyres could perform well in the winter in the city, but may not be adequate for snow-covered roads.
We fully agree with the expert of Continental; driving on winter tyres in the summer is not only less safe, but also less economical. The costs of possible damage liquidation could be much higher than the price of new tyres. However, with the health and lives of our relatives and other road users at stake, and given that seasonal tyre exchange contributes to our safety on the road, nothing can replace the driver's sober judgment.