**Winter, snow, icy surface, poor visibility. When braking in these weather conditions with summer tyres on and the speed of 100 km/h, the stopping distance is 16 meters longer, according to ADAC - a German automobile club. Changing your tyres regularly and ensuring their proper storage off-season increases your safety.
According to the Polish Tyre Manufacturers Association, 92 percent of drivers claim they change their tyres depending on the season of the year. When to do it? How to evaluate the condition of your tyres? Every driver should know this.
*How to evaluate the condition of your tyres
You should change your tyres as the seasons of the year change, but you should also check their condition regularly, independent of the weather. Frequently, your tyres need changing not because of a weather change, but because of their wear.
The most important criterion is the depth of the tread. According to the road traffic code, the depth of the tread for passenger cars is minimum 1.6 mm. However, experts claim that this value should not be applied. This relates in particular to winter tyres.
New treads have a depth of 8 mm. One can assume, then, that decreasing it to 1.6 mm completely changes the abilities and properties of a tyre. Therefore, it is recommended that you consider changing your tyres when their tread depth is reduced to 3 mm. The age of a tyre is also important. A tyre should not be used for more than 8 years from its manufacturing date, even if its tread is in a good condition and conforms to the applicable standards. Rubber, of which tyres are made, becomes harder and loses its flexibility with each season. Consequently, its grip, especially wet grip, is much worse. You can easily check the age of tyres on their outer sides. The two first figures stand for the production week. They are followed by the year of manufacture. This way you can easily check when a tyre was manufactured.
In addition to the tread and age of a tyre, you should also check its general shape. Any bumps, irregularities or even the slightest hint of cracks are a reason to change your tyres or at least have them inspected by a professional garage.
When to change tyres
You should change your tyres in the autumn and spring, unless they require immediate changing because of their poor condition. Summer tyres perform much worse than winter ones in the rainy, snowy and icy weather of October and November. When you drive your car with winter tyres on in late spring, you get an impression that they stick to the road surface too much and too hard, making driving difficult.
Naturally, you should not base your decision to change tyres solely on the calendar. October may be either surprisingly worm or cold, bringing even sub-zero temperatures. It may be equally difficult to decide when to replace the winter tyres with the summer ones. The best solution is to use the temperature criterion. Winter tyres should be replaced with summer ones when the average daily air temperature exceeds 7 degrees centigrade over a few consecutive days.
How tyres are changed
Tyre change requires removal of the wheels from the car, followed by removal of tyres from the wheels by means of a tyre changer. Then winter or summer tyres are placed on the wheels, following their cleaning and covering them with a special paste facilitating the mounting of the tyres. The tyres are then inflated with air or nitrogen. The latter decreases the pressure fluctuation caused by temperature changes. Car mechanics also balance the wheels and check the valves. The wheels are then initially screwed back on by means of a pneumatic impact wrench, and then tightened with a torque wrench. This protects them from being unscrewed. Directional tyres are marked "rotation," meaning that the rotation direction should follow the arrow. In turn, asymmetrical tyres are marked "outside," meaning that following the mounting of the tyres the inscription should be on the outside, as opposed to a tyre marked "inside."
Once you leave the garage, you should check the pressure in your tyres. It should be at the right level to ensure safety and extend the useful life of tyres, even by a few thousand kilometres.
Too low pressure causes the tread to collapse and results in intensive wear of the tyre edges and increased fuel consumption. On the other hand, as a result of a too high pressure, only the central part of the tyre has contact with the surface. Consequently, the wear of this part of the tyre is greater than that of the other parts, which affects the driving parameters. The recommended pressure is shown on a plaque or a label usually placed near the lock of the driver's door or on the inner side of the fuel filler cover.
**Winter vs. summer tyres
They differ in terms of the blend of the materials they are made of. Winter tyres contain more rubber, also the synthetic one, and silica. This blend makes tyres flexible even at low temperatures. At high temperatures, however, they become too soft and more vulnerable to wear.
Winter and summer tyres differ also in terms of the tread. The tyres intended for driving in cold and snowy weather have special grooves ensuring the right grip. Winter tyres have more of these grooves than summer ones. They are also deeper. They result in a greater stability of tyres in winter, and a reduced stability in summer, especially when driving fast. The braking efficiency is also decreased, especially on a dry and hot asphalt.
The tread on a winter tyre is divided into two large sections. The gaps between them remove water during rain and fill with snow when it snows, improving the braking efficiency.
The process of tyre change does not end with leaving a garage. If you want to use your tyres for a long time, you should also store them in the right conditions. How to properly store tyres? They should not be hung on hooks or placed one on top of the other, as this may affect their shape. A good idea is to place them in a vertical position next to each other, just as they are mounted on the car. You should also make sure that you change their angle once in a while during the storage period.
An increasingly popular solution is changing not just tyres but the whole wheels. This method requires purchasing new wheels, but reduces the cost of the seasonal change. Once you have a set of winter or summer wheels, you should pay attention to their position during the storage period. These can be hung on special hooks or placed horizontally one on top of the other, keeping in mind, that their position should also be changed every few weeks.
You can also store your tyres or wheels at a professional tyre garage, e.g. one of the some 500 tyre garages associated within the Motointegrator Partner chain, specializing in changing and repairing tyres. Use the website search engine to find the nearest garage.