Specialists do not recommend winter tires with a tread depth of less than 5 mm.

Specialists do not recommend winter tires with a tread depth of less than 5 mm
Depreciation of car tires varies from country to country: one car can participate in traffic where the remaining tread depth is 2 mm, in others 3 mm is not enough. Tires specialists in Latvia unanimously agree with another figure - 5 mm. Although tire manufacturers ensure that up to the legal limit of 4 mm - they fully perform their functions, the tread should be checked before the winter season. If its depth is less than 5 mm, it can be better utilized while new tires are fitted to the car.
“The tread depth for new car tires is usually about 8 millimeters, so most drivers will wear them out within 3-5 years to the legal limit. Before winter tire installation, I recommend that drivers check the tread depth and risk not to start with 4.5 or 5 mm - for a better season when grip is particularly important, buy new tires. At the end of the season, the tread of such tires will be worn to 4 mm or more, and it is very dangerous, ”says Martins Grīnbergs, Head of Sales at Goodyear in the Baltic States.
He adds that mounting old tires on the rear axle and mounting new tires on the front axle is not a good solution. All wheels of the car must have good grip and there is no axis that is less important than the other.
The difference is measured along the length of the car
One of the best researches over the past year, comparing different tires according to their wear level, was made by the German edition of "Auto Bild". Last winter, they tested new tires of the same model, up to 4 mm and up to 2 mm, under different conditions - between the tires, both summer and winter. The results for a particular race were different - it is natural that winter snow tires function better than summer tires, but the percentage drop in performance when tires wear out is similar.
First test - snow braking. New winter tires from 50 km / h to 0 km / h stop by 29.1 m, up to 4 mm worn tires - 33.5 m, and up to 2 mm worn tires - 34.9 m. The difference does not look great, but it is the speed allowed in the city, but the braking distance between 8 and 4 millimeters is 4.4 meters - this is the average length of the car. The tire with a 2 mm tread stops even 5.8 m further than the new one, but it is already over the length of the minibus.
The driveability properties of the snow test were measured by evaluating the speed at which the car wrapped around a particular tire begins to slip. Here the difference is only about 10 percent, but it is very important - for example, when driving in a city with a permitted speed (50-60 km / h), it will be possible to repair a car equipped with new winter tires, suddenly noticing an obstacle. . Used tires with a tread depth of 2 mm will fail to do so.
What is the difference in wet road cover? Even bigger. It should be noted that the speed of aquaplaning of tires with smaller treads is higher, which makes it harder to control the car.
It is advisable to evaluate the duration of the season
Naturally, as the tires get worse, the results shown by the cars are getting worse, but the tests described above and the like reveal another thing - the tread depth approaching the permitted limit, the deterioration of the properties occurs very quickly. On dry cover it is not as prominent, but on snow - calculated in meters. But when comparing the handling characteristics, tire wear from 8 mm to 4 mm in car properties is similar to wear from 4 mm to 2 mm.
Particularly large differences in properties are on wet roads, but this is most common in the Baltic States.
“The difference between new and used tires is great. In most of the tests, the tire tread depth decreases from 8 mm to 4 mm, but the deterioration occurs very quickly. That's why tire manufacturers recommend replacing tires without waiting for the last "legal" border, and installing new ones while driving does not raise any doubts about safety, "says Grinberg.
For this reason, it is not worth installing winter tires whose tread depth has already fallen to 5 mm. In the middle of the season, it will have fallen to 4 millimeters later, perhaps even more so, and driving with such a car will not only be legally illegal but also absolutely unsafe.