What is the difference between a summer and a winter tyre?
There are two important differences between winter tyres and summer tyres. One of these is immediately visible: the pattern. The other you do not see, but you do feel it: the rubber composition. Both differences influence the braking distance, rolling noise and rolling resistance.
1. Pattern summer and winter tyres
A significant difference between summer tyres and winter tyres are the notches in the patterns blocks of the winter tyre: the sipes. The sipes provide more grip on the road when braking and accelerating. While driving, the patterns deforms and the sipes work like ‘grippers’ on the road surface. Sipes are usually made perpendicular to the tyre in order to creacte a lot of grip when accelerating and braking. For stability in bends, sipes are also applied longitudinally (vertical), and zigzag sipes are applied.
A lot of force must be applied to the summer tyre pattern in order to deform the pattern block. Moreover, the tyre only has one gripping point on the road surface.
The pattern block can move easily thanks to the sipes in the pattern of the winter tyre. This results in four gripping points on the road suface with only small forces.
2. Rubber composition summer and winter tyres
A summer tyre has a different rubber composition compared to a winter tyre. The running surface (the part of the tyre in contact with the road surface) of a winter tyre is namely provided with a rubber composition which remains flexible at low temperatures, that is to say: temperatures below +7° Celsius. This enables the pattern blocks to deform more easily and so they have more grip. The difference in hardness between the rubber of a summer tyre and that of a winter tyre can be clearly seen in the figures below. The rubber of a summer tyre does not deform easily at zero degrees, while the rubber of a winter tyre is then still flexible.
Braking distance summer and winter tyres
Winter tyres are not only safer in winter conditions than summer tyres, but also on a cold and wet road surface. Especially when braking. The difference in braking distance between summer and winter tyres can be clearly seen in the table below:
Note: The braking distances in the examples above have been measured with ‘standard vehicles’. The examples provide an illustration. The braking distance is dependent on many factors, including: the type of car, the car’s weight and load, the starting speed, the brakes, the tyre and asphalt temperature, the weather conditions, the condition of the road surface, the tyres fitted and the status of those tyres, such as pattern depth. And do not forget that the braking distance is also defined by adapted driving behaviour in winter conditions and you reaction speed.
Rolling noise summer tyres and winter tyres
Tyres which roll over the road surface make a noise. Dutch motorways are getting steadily busier and therefore the noise nuisance is also on the increase. The choice of the correct type of tyre contributes to a eduction of the rolling noise. Winter tyres have a softer rubber composition than summer tyres. At low temperatures, the rubber of summer tyres becomes relatively hard. This causes more rolling noise. In the winter, winter tyres with the snowflake symbol make less (rolling) noise than summer tyres.
Rolling resistance summer tyres and winter tyres
Rolling resistance is the resistance experienced by a tyre when it rolls over the road surface. The rolling resistance is caused principally by the deformation of the rubber of the tyre and damping of the rubber. The deformation increases the contact surface of the tyre with the road surface. And the size of the contact surface defines the rolling resistance.