19.4. Disks and tires

When replacing a disk or the tire surely replace the rubber valve with the nipple.

Tires and rims (on disk wheels) are important elements of a design of the car.
Installation and repair of tires demands the special tool and professional skills. Only experts have to perform these works.
For safety reasons the movements it is possible to change tires only in couples and only on one axis. Less worn-out tires should be put always on forward wheels.
On all wheels it is necessary to install only radial tires of the same design, the identical size (with an identical length of a circle) and it is desirable with the identical drawing of a protector of the tire. In the presence of the drawing of the protector defining the direction of rotation of tires on the side surface of the tire arrows indexes are put. In this case it is necessary to observe the direction of rotation of the tire strictly. At the same time optimum operational qualities of the tire, coupling with a wet paving are provided and the wear and noise created by the tire decrease. If the tire is damaged, as a temporary measure it is possible to install for a while the tire with the direction of rotation opposite to set.
On the all-wheel drive car, besides, all tires have to be identical model of the same manufacturer. Otherwise a viskomufta because of the arising difference in the frequency of rotation of wheels of both axes it is undesirable will increase the draft share falling on a back axis. It can lead to breakage.
Various depth of the drawing of a protector of tires of forward and back wheels, for example as a result of wear, is not so important. However it is recommended to install tires with a bigger depth of the drawing of a protector on forward wheels: if tires of forward wheels are worn-out more, than tires back, length of their circle is less and therefore they rotate quicker. In transmission additional tension results, and tires wear out quicker.
At the choice of tires it is necessary to know their marking.

Fig. 13-2. Wheel: 1 – tire; 2 – valve; 3 – disk; 4 – bolt of fastening of a wheel of M14x1,5x27,5, 120 N · m; 5 – lock cylinder; 6 – decorative cover; 7 – decorative slip; 8 – small weights

Fig. 13-3. Arrangement of marking of the tire

Radial tires (fig. 13-3) have on a tire sidewall marking, for example:
195/70 R 15 89 H, where
195 – width of a profile of the tire, mm;
70 – tire profile height relation to its width, %;
R – an arrangement of threads of a cord of a framework – designation of the radial tire;
15 – diameter of a rim of a disk, in inches;
89 – index of admissible loading capacity of the tire;
H – index of speed, km/h.

        Maximum index
speeds       speed, km/h
                          Q 160
                          S 180
                          T 190
                          H 210
   V                       240
                          W 270

Date of issue is specified also on a tire sidewall (in some cases only on the internal surface of the tire).
DOT – manufacturer;
CU – code designation of the manufacturer;
L2 – the tire size;
UM8 – tire type;
507 – date of production (the 50th week 1997);
TUBELESS – the tubeless tire (TUBETYPE – chamber).
Rims are marked too.
For example, designation 6J x 16 is deciphered as follows:
6J – disk width, in inches;
J – height of an onboard edge of a disk;
x – a deep disk;
16 – landing diameter of a disk, in inches.