THE INFLUENCE OF TIRE PRESSURE ON THE DYNAMIC CHARACTERISTICS OF THE CAR AND RESISTANCE TO MOVEMENT

The main task of car tires is to provide the necessary grip characteristics. When the tire pressure is normal, the load at the point of contact of the tire with the road surface is distributed evenly and at the same time good controllability, maneuverability and optimal fuel consumption are ensured. The optimal pressure value for a specific car brand is determined not by the tire, but by the car manufacturer, because the same size can be mounted on different models of cars with different weights and other characteristics. Usually, information about the pressure recommended by the car manufacturer is indicated either in the technical documentation for the car, or on a plate that can be placed on the end of the driver's door, the side pillar on the driver's side, the fuel filler flap or in the glove compartment. There is the label indicates the level of cold working pressure for the front and rear wheels, the maximum load on the car and the recommended tire size. In addition, the pressure value can be affected by such factors as the weight of the car, the size of the tires, the distribution of the load inside the car and even the time of year. It should also be taken into account that the pressure can change with climate change. In summer, as the temperature rises, so does the pressure in the tires. For example, when the temperature rises to 25°C, it increases by about 0.8 bar. And if the load is full, the pressure will be even greater. That is why car manufacturers indicate the permissible pressure value for a loaded car. This is an extremely important parameter for ensuring safety, which cannot be ignored. In winter, when the air temperature drops, the pressure in the tires also drops by about 0.8 bar, which should also be taken into account when pumping up the tires. The rolling resistance coefficient f of Kleber Viaxer tires 175/70 R13 82T was estimated along the coasting path of a Lada-112 car. Increasing the air pressure by 0.05 MPa reduces f by 1.3%, decreasing the pressure by 0.05 MPa increases f by 1.7%. Key words: tire, car, drag coefficient, friction force, acceleration, pressure, temperature.