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8.5.3. Important data on tires

On a sidewall of the tire there is a number of digital and alphabetic references by means of which the producer codes the characteristics of tires ordered by technical documentation. Many drivers are interested first of all the tire size. So, for example, 205/65 R15 means that width of section of the tire makes 205 mm. The second shows the attitude of height and width of the tire. In this example it makes 65%. Than less this indicator, especially and wide tires are flat. The letter "R" designates that the tire is radial. The number following a letter expresses diameter of the tire in inches.
   Maximum speed
One more letter in this row designates the most admissible speed for this tire. The tire having the letter "S" in designation is calculated on the maximum speed to 180 km/h, a letter "T" – to 190 km/h. For the maximum speed of 210 km/h the tire has the letter "H".
If you go in the winter by ordinary winter "M+S" tires, it is necessary to limit speed. The tire with the letter "Q" allows the movement with a speed no more than 160 km/h.
   Term of production and ECE standard

Fig. 7.22. It is easy to determine number ESE by capital letter E and to the digital code of the country manufacturer following it: for example, 1 – Germany, 4 – Holland

Three-digit number "DOT" contains information on date of production of the tire. Since 1990 under this number the small triangle is put. For example, number 187 specifies that this tire was made on the 18th week 1997. The new tires manufactured after October 1, 1998 have to have number of the certificate of the Economic Commission for Europe (fig. 7.22) on a sidewall. This number certifies that this tire is production certified by the Economic Commission for Europe on compliance to the quality standards established to it. At installation on the car of the tires manufactured after October 1, 1998 without number of the certificate permission to operation of the car is cancelled.

Fig. 7.23. Wheel parameters: A – rim width in inches; B – profile of an onboard zakraina of a rim; C – diameter of a wheel, in inches; D – diameter of an opening of fixture; E – the combined ring ledge on the landing shelf of a rim; F – depth of a press fitting, mm

The rim size according to standards is always specified in inches. So, for example, the code 7 1/2 J x 15 means a disk with a deep rim (h) 7,5 inches wide and with a diameter of 15 inches. The letter J means a form of an onboard zakraina of a rim. Feature of a deep rim following: for improvement of landing of tires on the basis of a rim there is a round ledge (хамп). It interferes with failure of the tire from a disk at turn at a high speed (fig. 7.23).

   Winter tires — for snow and ice

Fig. 7.24. Comparison of a brake way of summer and winter tires on the car without ABS when braking with blocking on ice (from the speed of 30 km/h):
winter tires:
brake way – 57 m
summer tires:
residual speed of the car – 12 km/h;
brake way – 68 m

Winter tires increase safety at the movement on a snow and ice covering in comparison with summer (fig. 7.24 and 7.25).

Fig. 7.25. Comparison of a brake way of summer and winter tires on the car with ABS on a snow-covered paving (from the speed of 50 km/h):
winter tires:
brake way – 35 m
summer tires:
residual speed of the car is 23 km/h;
brake way – 43 m

Winter tires are made from special composition of rubber with a big share of natural rubber which at temperatures below +7 °C behaves on a paving better. Guarantee of reliable transfer of forces at the movement and braking is also the protector at least 4 mm high — smaller is not resolved for winter tires. Winter tires should be installed on all four wheels at once — the combination from summer and winter tires can be dangerous.
   Installation of winter tires on wheels
At the beginning of winter and fall it is possible to save on expensive replacement of tires if to get the second set of suitable disks. Wheels after each remount have to be newly balanced. When driving on snow it is recommended to increase pressure in tires by 0,2 bars.
If the most admissible speed for winter tires is lower than the speed limit of your car, for a reminder on it it is recommended to paste in the field of your sight (not on a windshield) a reminder on it.

Fig. 7.26. If you often go by flat tires and at the same time with big loading, it can lead to partial stratification of the tire

Correct storage of tires
After seasonal "pereobuvka" the removed set of tires needs to be stored correctly. For this purpose best of all the dry, cool and dark room approaches. Gasoline, oil, lubricant and chemicals need to be held far away from tires — all this destroys rubber.
Execute the following operations:
1. Mark the direction of the movement and position of tires (software — a lobby right, PL — a lobby left, ZP — back right, ZL — back left).
2. Wash the removed tires water and carefully dry. Remove foreign objects from protector flutes.
3. Put tires with rims lying, it is the best of all on the old wooden pallet.
4. Tires without rims should be stored in vertical position, from time to time turning them.

How to increase service life of tires
1. Do not exceed the maximum speed on which your tires are calculated. It belongs first of all to the tires having marking of "M+S" of category Q (160 km/h). Speeding increases wear of tires, and at worst leads to their gap (fig. 7.26).
2. Avoid the movement at the maximum speed if your car is strongly loaded. It is possible to make simple check, having touched tires with a hand. If its heating does not exceed body temperature — everything is all right. Hot tires — the disturbing signal indicating the insufficient pressure or other malfunction. In this case the tire should be dismantled and checked at the expert.
3. If you often go with a high speed, install on the car of the tire of higher high-speed class, than that is demanded by the registration certificate of the car (for example, "V" instead of "N").
4. At the parking you watch that sidewalls of tires did not rub about a border. On borders or hillocks come around slowly and always at right angle.