- remove the rubber protective cap;
- unscrew the cap-key of the inflation valve;
- lightly wet the valve and make sure there are no air bubbles. If an air bubble forms, this indicates an air leak through the valve:
- turn the key cap over and screw it onto the valve core;
- recheck the valve for leaks. If the valve leaks air, it must be replaced;
- be sure to install the protective cap.
All tires have a built-in wear indicator in the form of control strips that are exposed when the tread depth decreases to 1.6 mm, after which the tires are considered worn out (arrow, Fig. 2.25)
The optimal tire tread depth is 3.0 mm or more, for winter tires - 4.0 mm or more. The efficiency of winter tires ("M+S") on snow, mud and slush drops already at a tread depth of 4 mm.
The control strips are located around the entire circumference of the tire where the "TWI" marks are located (Tread Wear Indicator). Checking tire wear should be done in several places ("TWI") simultaneously, as tire wear depends on many factors.
The nature of the tread wear can be used to determine the cause of it, Fig. 2.26.
Thus, tire (1) shows wear caused by prolonged driving with increased pressure, and tire (2) - with insufficient pressure. Wear of tire (3) with characteristic rounded edges on one side of the tread pattern and sharp on the other side is caused by wheel alignment violations. With significant deviations (10-15 mm) from the recommended toe, tires can be worn out in less than 1,000 km. Tire (4) has uneven tread wear due to wheel camber violations. This is especially noticeable with a large difference in camber between the left and right wheels. Type of wear (5) in the form of one or two "bald spots" is a consequence of increased runout of the brake disc or drum. These "bald spots" may be accompanied by similar diametrically located "bald spots" if the brake drum of the parking brake has increased ovality or lateral runout of the brake disc. A less pronounced "bald spot" appears as a result of emergency braking at high speed when driving on a concrete road.
Tire (6) shows patchy wear resulting from large angular oscillations of the front wheels or one wheel.
The main causes of spotty tire wear are:
- play in the steering rod joints;
- malfunction of the front shock absorbers or one of them;
- serious wheel imbalance;
- loose steering gear mount.
Damaged wheels are not repaired, they are replaced with new ones, which increases safety.
Pay special attention to the absence of punctures and cuts on the tires. If the cuts reach the tire frame, it must be replaced.
It is recommended to change tires, including the spare tire, at least once every 6 years, even if the service life of the tires is 10 years. Balancing should be performed every time a tire or wheel is replaced. The pressure in the spare tire should be 0.5 bar higher than the maximum prescribed value indicated on the plate (see fig. 1.58) are shown on the end of the driver's door.
Install the wheel mounting bolts dry and tighten them crosswise to a torque of 140±10 Nm (14.0±1.0 kgf·m).
Note: For safety reasons, only tires of the same type and tread pattern should be installed on the vehicle.