Recently, " Changjin Lake " was screened. The film tells the story of the officers and soldiers of our volunteer army in a heroic and tenacious battle with the US military on the front line of Changjin Lake, North Korea during the harsh environment of minus 40 degrees Celsius. When the battle occurred, the minimum temperature in Changjin Lake area was around minus 35℃. The volunteers have been ambushing on the ridge for a long time, with stronger winds and lower temperatures as low as minus 40℃.
people survived in extreme low temperatures and their equipment was extremely difficult, but they were the same even though they were inanimate. The steel guns in the hands of the soldiers were frozen and they could not pull the bolts; the car engines were frozen and they could not start; the car tires were frozen and the rubber was hard, and many trucks in our army slipped down the cliffs of ice and snow blocking the road due to slippage...
Why do there be winter tires? Starting from a picture...
If you want to say that the car engine is frozen, everyone still understands it, but the car tires severely slipped at extremely low temperatures and caused overturning, so many friends in South cannot understand it. ——Of course this is not unfamiliar to Northern riders. Because northern riders have the habit of using winter tires during the severe cold winter period.
However, I have come into contact with many northern riders. Although they know that they need to use winter tires, they don’t know when to use them. Some people say that it is used if it is below 0 degrees; some people say that it is necessary to use it as soon as winter begins; some people say that it is necessary to use it when it is snowing, and the statements are different. So today I took this opportunity to talk about this topic. ——First let me show you a picture "Temperature-Friction Coefficient Curve Chart of Different Types of Tires".
"7-degree critical point" is an inescapable pain
In the figure, the red one is the "temperature- friction coefficient " curve of summer tires; while the gray one is the "temperature-friction coefficient" curve of eastern tires; we can see a "7-degree" intersection point from the figure.
First of all, the summer tire: starting from 50 degrees, as the temperature decreases, the friction coefficient gradually decreases; when the temperature drops to 7 degrees, the friction coefficient of the tire decreases from "excellent" to "good" range; and as the temperature further decreases, the friction coefficient of the tire begins to enter the "unexpected" range.
Then there is summer and winter tire: starting from -30 degrees, as the temperature increases, the friction coefficient gradually decreases; when the temperature rises to 7 degrees, the friction coefficient of the tire decreases from "excellent" to "good" range; and as the temperature rises further, the friction coefficient of the tire begins to enter the "unexpected" range.
summer tires intersect with the "temperature-friction coefficient" of winter tires at exactly 7 degrees, and the friction coefficient performance between summer tires and winter tires is just "inverse". ——This is the "7-degree principle" recognized by the tire industry.
European regulations: The surface temperature is below 5 degrees, and summer tire testing is prohibited!
When the ambient temperature of the tire in summer is lower than 7 degrees, the rubber becomes hard, so the relative friction coefficient with the ground is greatly reduced, so the performance is significantly affected. The most intuitive phenomenon is that at the same speed, the distance of emergency braking (acute braking) becomes significantly longer. For example, if the brake distance is 37 meters when the temperature is 25 degrees, the brake distance will be extended to 42 meters when the temperature is 2 degrees.
Of course, the 7 degrees here refers to the temperature. In fact, the more professional scale is "surface temperature". Usually the surface temperature is higher than the temperature in summer, while the surface temperature is lower than the temperature in winter. ——In the tire industry, the most precise way for professional engineers to say is: the surface temperature range where tires can maintain normal grip performance in summer is between 5 degrees and 50 degrees (too high temperature will cause tire grip performance to deteriorate).
In fact, any professional tester who is engaged in tire testing knows that in the world-recognized EU tire testing specification (ECE-R117 system), it is stipulated that if the surface temperature is less than 5 degrees or higher than 50 degrees, summer tire performance testing business is prohibited.Because the tire performance deteriorates at this time, the measured results are not accurate, and it is useless to test it!
html below 00 degrees, you must use winter tire , because the road surface may freeze at any time! The topic ofhas gone far. After all, we ordinary car owners don’t need to be so professional and precise. We just need to look at the temperature. Of course, in the environment with temperatures below 7 degrees, summer tires do not mean that they cannot be used, but their performance will be greatly reduced. But if the temperature is lower than 0 degrees, maybe things are not that simple:
We know that water below 0 degrees will freeze. If there is water on the road surface, thin ice will form under the action of low temperature. I don’t think everyone knows what the consequences will be if the tires are pressed on thin ice in summer? ——So when the temperature is below 0 degrees and the road surface will freeze, it is prohibited to continue using summer tires. At this time, winter tires must be replaced to ensure safety!
talks about diesel freezing points and cold filter points, they are actually related to tires!
However, the weather changes themselves are irregular. Maybe the temperature is 4 degrees today and the temperature will be as low as minus 1 degrees tomorrow. We ordinary car owners cannot keep the weather forecast every day. So how can we judge the simplest thing to "whether it's time to change to winter tires"? Here I will share with you a "private experience" for your own use. This "private experience" is related to diesel! You heard it right!
We know that diesel has two indicators: "freezing point" and "cold filter point". " freezing point " is the temperature point when diesel completely freezes into "jelly", and it is also the label of diesel. For example, diesel No. 0 means "the freezing point of diesel is 0 degrees"; diesel No. 10 means "the freezing point of diesel is minus 10 degrees".
But few people know the "cold filter point" of diesel. Although diesel below the "cold filter point" is still a liquid, many small crystals will condense in the liquid (like salt). These crystals will block diesel filter , so diesel can only be used at temperatures above the "cold filter point"!
"Fresh tires with the gas station", private room tricks are simple and practical
Therefore, my country has strict regulations on the use temperature of diesel: "No. 0 diesel" is used uniformly in temperatures above 4 degrees; "No. 0 diesel" is used uniformly between minus 5 degrees and 4 degrees; "No. 10 diesel" is used uniformly; between minus 14 degrees and minus 5 degrees, "No. 20 diesel" is used uniformly; and so on - Speaking of this, have you guessed my "private experience"?
If the gas station around you is still supplying "Diesel No. 0", you can use summer tires with confidence and boldness. Because the temperature is above 4 degrees at this time; if you find that the gas station around you starts supplying "-10 diesel", you should change to your winter tires. Because the temperature is between 4 degrees and minus 5 degrees, the road surface may be at risk of icing.
has been used after changing into winter tires. Until the beginning of the spring of the next year, the local gas stations began to supply "No. 0 diesel" again, and then replace it with summer tires. This method is simple, practical and easy to remember. You don’t need to pay attention to the weather forecast every day, you just need to glance at the sign of the nearby gas station.
