Winter vs. All Season tyres: what, how and when to choose them

As winter approaches, when it gets colder and temperatures drop under the critical 7°C cut-off point staying low until spring, summer tyres cannot provide the same efficiency on the road because of their rigid structure. The time has come to switch to winter tyres. Their soft compound performs well in the cold season at sub-zero temperatures. They guarantee good grip even on icy and slippery surfaces to the advantage of safety in addition to securing performance and high levels of comfort. 
All Season tyres, instead, combine the qualities of summer and winter tyres and are suitable all year round. So when the temperature start dropping, their medium consistency, half way between rigid summer tyres and softer winter tyres, makes them adaptable and suitable for prolonged used regardless of the climate. A versatility like this comes with limitations.

The stiffer compound of winter tyres means that they can reach optimal operating temperature more rapidly and support the ride with the requisite elasticity in cold weather and on icy roads. Under the 7°C mark, studies and improvements have contained braking distances within 10% on wet roads and 20% on snow. Merit for this goes to the tyre structure but also to the specific tread pattern. The tread of a winter tyre has characteristic sipes, i.e. the blocks that form the pattern on which the tyre stands, and deep grooves working as draining channels. The sipes displace the collected mud and snow so that the tyre can perfectly grip on the tread surface and the grooves dispose of the water on wet roads to prevent aquaplaning. This spells maximum efficiency on all surfaces at cold temperatures without using snow chains. 
The tread pattern of an All Season tyre, on the contrary, is the result of a targeted functional balance. Efficient at high and low temperatures, on sunny days or in rainy days, on wet and dry roads alike, the tread pattern is designed to perform well in all conditions, although never at the level of summer and winter tyres in extreme conditions in the respective seasons, precisely because of its versatility. 

Regardless of characteristics and type, it is essential for tyres to be in excellent conditions to ensure maximum efficiency in terms of safety and performance. Periodically checking tyre conditions is recommended. Tyre wear also has repercussion on fuel efficiency. The tyres must be replaced when the block depth is less than the 4 mm limit. A quick and easy method to do this is to take a coin. For winter tyres, position a 2 Euro coin in the groove. If you can see the edge of the coin, the tyre should be replaced. Conditions are important because the wheels must transmit the maximum level of safety on bad road. As a consequence, their performance is no longer optimal when temperatures remain constantly higher than 7°C and their soft structure tends to suffer and slip under the effect of the high stress. All Season tyres instead perform well even in these conditions although they are still a far cry from offered by summer tyres.

The letters M+S or M&S or M-S printed on the sidewall of All Season tyres claims their “mud and snow” nature. They are developed for various types of vehicles, from small city cars to versatile SUVs and fast sports cars, that run at high speed. Various sizes are available. They differ from summer tyres for having a rounder profile and for the indications shown in the marking. 
The M+S lettering may appear next to a three-peak mountain with snowflake symbol, or simply 3PMSF, like on the Pirelli Cinturato All Season tyres. This marking means that the tyre has passed a specific test designed to verify its behaviour on demanding routes compared to an M+S reference model. If the results of the tyre under test expressed in percentage are higher than or equal to 7%, the test has been passed. Performance can be improved by up to 30%. 
A 3PMSF winter tyre means being able to effectively tackle even the most extreme conditions and merit for this goes to the development work of engineers on each components: the materials used for making the tyre account for three fourths of the total result, in addition to the specific pattern with special shaped sipes.
Turning back to compounds, also available for different vehicle types with different engine displacement, All Season tyres are suitable for all motorists seeking sets that ensure constant, long-lasting performance but at the same time do not expect the extreme results which would be achieved by summer or winter tyres in their respective seasons. Anyone demanding peak performance from their respective cars on snow or in very cold conditions is advised to fit a set of winter tyres as these offer the best road-hold properties while guaranteeing the highest degree of safety for drivers.

Characteristics of all-season tyres, designed to be employed in all weather conditions:

Do not forget that also all-season tyres should respect the ideal tyre size and pressure recommended by the car manufacturer.