Max Speed
Another letter in this row indicates the maximum allowable speed for this tire. The tire with the letter in the designation «S», designed for a maximum speed of up to 180 km / h, the letter «T» – up to 190 km/h. For a top speed of 210 km/h, the tire has the letter «H».
If you drive in winter with normal winter tires such as «M+S», you should limit the speed. Tire with letter «Q» allows movement at a speed of not more than 160 km / h.
Production time and ECE standard
Pic. 7.22. The ECE number is easily identified by the capital letter E followed by the numeric country code of the manufacturer: for example, 1 - Germany, 4 - Holland
Information about the date of manufacture of the tire contains a three-digit number «DOT». Since 1990, a small triangle has been placed under this number. For example, the number 187 indicates that the tire was manufactured in week 18, 1997. New tires manufactured after October 1, 1998 must have the Economic Commission for Europe certificate number on the sidewall (pic. 7.22). This number certifies that the tire is a product certified by the Economic Commission for Europe to meet its quality standards. If tires manufactured after October 1, 1998 are installed on a vehicle without a certificate number, the permit to operate the vehicle will be cancelled.
Pic. 7.23. Wheel options: A - rim width in inches; B - profile of the side flange of the rim; C is the wheel diameter, in inches; D is the diameter of the fastener hole; E – combined annular protrusion on the rim seat; F – pressing depth, mm
Wheel disks
The size of the rim according to the standards is always indicated in inches. So, for example, the code 7 1/2 J x 15 means a disc with a deep rim (X) 7.5 inches wide and 15 inches in diameter. The letter J stands for the shape of the rim flange. The feature of the deep rim is as follows: there is a round protrusion on the base of the rim to improve the fit of the tires (hump). It prevents the tire from slipping off the rim when cornering at high speeds (pic. 7.23).
Winter tires - for snow and ice
Pic. 7.24. Comparison of braking distances of summer and winter tires on a car without ABS when braking with blocking on ice (from a speed of 30 km/h):
- Winter tires:
- braking distance - 57 m
- summer tires:
- residual speed of the car - 12 km/h;
- stopping distance - 68 m
Winter tires improve safety when driving on snow and ice compared to summer tires (pic. 7.24 and 7.25).
Pic. 7.25. Comparison of braking distances of summer and winter tires on a car with ABS on a snowy road surface (from a speed of 50 km/h):
- Winter tires:
- stopping distance - 35 m
- summer tires:
- residual vehicle speed 23 km/h;
- stopping distance - 43 m
Winter tires are made from a special rubber compound with a high proportion of natural rubber, which behaves better on the road surface at temperatures below +7°C. The guarantee of reliable transmission of forces during driving and braking is also a tread height of at least 4 mm - a smaller one is not allowed for winter tires. Winter tires should be installed on all four wheels at once - a combination of summer and winter tires can be dangerous.
Mounting winter tires on wheels
You can save money on expensive tire changes at the beginning of winter and autumn if you purchase a second set of suitable wheels. Wheels must be re-balanced after each remount. When driving on snow, it is recommended to increase the tire pressure by 0.2 bar.
If the maximum speed limit for winter tires is below the speed limit of your vehicle, we recommend sticking it in your field of vision to remind you of this (not on the windshield) a reminder of this.
Pic. 7.26. If you often drive on flat tires and at the same time with a large load, this can lead to partial delamination of the tire
Proper tire storage
After seasonal «changing shoes» the removed set of tires must be properly stored. For this, a dry, cool and dark room is best suited. Gasoline, oil, grease and chemicals should be kept away from tires - all of these destroy rubber.
Perform the following operations:
1. Mark the direction of travel and the position of the tires (PP - front right, PL - front left, ZR - rear right, ZL - rear left).
2. Wash the removed tires with water and dry thoroughly. Remove foreign objects from the tread grooves.
3. Tires with rims should be stored lying down, preferably on an old wooden pallet.
4. Tires without rims should be stored upright and rotated from time to time.
How to increase tire life
1. Do not exceed the maximum speed for which your tires are designed. This applies in particular to tires marked «M+S» category Q (160 km/h). Speeding increases tire wear and, in the worst case, blows them out (pic. 7.26).
2. Avoid driving at maximum speed if your vehicle is heavily loaded. You can make a simple check by touching the tires with your hand. If its heating does not exceed body temperature, everything is in order. Hot tires - an alarm indicating insufficient pressure or other malfunction. In this case, the tire should be dismantled and checked by a specialist.
3. If you often drive at high speeds, install tires of a higher speed class than required by the vehicle's registration certificate (For example, «V» instead of «H»).
4. When parking, make sure that the sidewalls of the tires do not rub against the curb. Drive over curbs or bumps slowly and always at right angles.