In radial tires, the cords are located along the shortest path between the tire beads. The breaker belt surrounds a thin and resilient carcass and provides tire stability.
In tubeless tires, the tube is replaced by a vulcanized inner layer with high airtightness. The bead of such a tire must be installed on the rim of the disc securely and tightly. The absence of a tube in the tire reduces the mass of the wheel and simplifies its installation on the rim.
Tire markings are printed on the sidewall. Tire width, construction and rim diameter are the minimum information required for tire marking.
Knowing the tire markings helps when choosing them (see fig. 10.2). Radial tires have the following markings, for example: 215/55 ZR1693Y
215 - tire profile width, mm.
55 - the ratio of the height of the tire profile to its width x100.
This ratio for passenger car tires ranges from 60 to 80. A ratio of 35 indicates that the tires are designed for sports cars.
Regardless of the value of this ratio, one tire diameter is used. Low profile tires (with a small ratio of the height of the tire profile to its width) provide high vehicle stability when cornering.
2R - the location of the cords - the letter designation for the radial tire.
16 — disk rim diameter, inch,
93 - index of permissible load.
Y is the speed index.
Data containing information about the identification code of the tire and the date of its manufacture, as well as information about the maximum load capacity and inflation pressure, is located near the DOT symbols on the sidewall of the tire.
In the grooves of the tire tread pattern there are "tire wear indicators" 1.6 mm high located at right angles to the direction of translation of the tire. These indicators range from six to eight (depending on the manufacturer) placed at equal distances around the circumference of the tire. Tire sidewall markers (e.g. letters "TWI" or an icon in the form of a triangle) show the location of the tire wear indicators.
Tires can be used up to a profile depth of 1.6 mm, that is, the profile grooves must have a depth of at least 1.6 mm over the entire surface of the tire. However, for safety reasons, it is recommended to change tires at a profile depth of 2 mm.
M+S tires have sufficient grip on snow with a profile depth of at least 4 mm.
Tire instructions
Optimum tire performance is only achieved when tires of the same design are fitted to all wheels of the vehicle.
During installation, do not install tires on a damaged, deformed rim with signs of corrosion.
When installing a directional tire (identified by the arrow on the sidewall of the tire) it must be in the correct direction of rotation. This will ensure optimum tire behavior in terms of aquaplaning, traction, noise and traction. If, when replacing a punctured wheel, a tire with rotation against the specified one is temporarily installed, then its use in this mode should be short-term.
Tire life depends on the following factors:
- Tire pressure.
- The nominal air pressure values for summer tires are indicated on a sticker on the inside of the fuel filler cap (see fig. 10.3).
- It is especially important to maintain the recommended air pressure in the tires when driving at high speeds. Therefore, the air pressure in the tires should be checked at least once a month and before every long trip.
- In this case, do not forget to measure the air pressure in the spare wheel.
- Tire pressure should always be checked when the tires are cold. With increased air pressure in hot tires, do not bleed air from the tire. If the load changes significantly, the air pressure in the tires should be changed accordingly.
- On vehicles with full-size wheel covers, there are extensions instead of dust caps to improve ventilation. It is not necessary to unscrew these extensions when checking and adjusting the tire pressure.
- Under-inflated or over-inflated tires shorten their lifespan and impair driving performance.
Constantly checking the condition of the tires will allow you to detect intensive wear in a timely manner and eliminate its cause, which will help to avoid more serious consequences.
Rupture or delamination of the tire tread. When driving at high speed for a long time, low-pressure tires do a lot of lateral deformation of the tires, as a result of which the tires become very hot. This can lead to partial separation of the tire tread and even to a rupture. At the same time, such defects often remain hidden for a long time, and with an increase in load or driving at high speeds, instant destruction of the tire can occur.
Wear on the outer side of the tire (front tire) occurs when cornering at high speeds. In the presence of such wear, it is recommended to rearrange the tires from the front axle to the rear axle of the car.
The wear of the outer sides of the tread occurs when the vehicle is driven with reduced tire pressure.
Uniform intense wear is probably due to a faulty shock absorber.
Uneven wear (in several places) occurs when the wheel is out of balance. The wheel needs to be balanced.
Places with heavy wear appear when braking with a locked wheel. It should be noted that even ABS cannot prevent short-term blocking of the wheel.
Unilateral tire tread wear. Incorrect wheel alignment not only causes increased tire wear, especially one-sided wear, but also contributes to a decrease in traffic safety.
Severe wear in the middle of the tire tread profile. Occurs due to the frequent movement of the car at the maximum speed of the tire, as a result of which, due to the action of centrifugal forces, the tire tread becomes convex in the center and wears out intensively. This type of wear is most pronounced on the rear wheels, with increased pressure in them.
Too low tire pressure leads to increased fuel consumption.
Overcoming sharp turns at high speeds, rapid acceleration and hard braking - all this increases tire wear.
Tires with varying degrees of tread wear are recommended to be swapped according to the scheme when a tire is moved from one vehicle axle to its other axle. A decrease in the depth of the tire tread pattern is accompanied by a decrease in the thickness of the protective layer of the cord and tire carcass. In addition, a decrease in the depth of the tire tread pattern leads to a disproportionate increase in the braking distance of the car. For example, the braking distance of a front-wheel drive passenger car from a speed of 100 km/h with a tread depth of 8 mm is 75 m, and at a depth of 2 mm it reaches 129 m. tire profile and tire material quality.
Mounting and repairing tires requires special tools and professional skills. These works should only be carried out by professionals.
For reasons of traffic safety, if possible, change the tires not individually, but along the axles. Less worn tires should always be placed on the front wheels.
On a four-wheel drive vehicle, in addition, all tires must be the same model from the same manufacturer. Otherwise, the visco clutch, due to the resulting difference in the speed of the wheels of both axles, will undesirably increase the share of traction attributable to the rear axle.
The different tread depths of the front and rear tires, for example as a result of wear, are not so important. However, it is recommended to install tires with a greater tread depth on the front wheels - if the front wheel tires are worn more than the rear wheel tires, they have a smaller circumference and rotate, therefore, faster. Therefore, there are additional stresses in the transmission, and the tires wear out faster.
If the spare wheel tire is different in design from the rest of the vehicle tires (for example, winter or wide-profile), then such a spare wheel should only be used for a short time in the event of a failure of one of the vehicle's tires and with a corresponding increased caution in driving. Instead of such a wheel, the old wheel should be installed again as soon as possible.
Never put a used tire on a car if you don't know where and how it worked before.
Tires in the front wheels provide a vehicle run for a distance of 15,000-35,000 km, on the rear wheels - 30,000-50,000 km. If the car is rarely used, then regardless of the mileage, tires must be replaced after 7-8 years, since over time the tire material (rubber compound) is destroyed.
Pic. 10.1. Tubeless radial tire PKW-Reifens
1 - protector
2 - base
3 - nylon cord
4 - steel breaker
5 - tire carcass
6 - airtight inner layer
7 - sidewall
8 - board
9 - bead core
10 - reinforcing thickening
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