14.1. General information
Modern tires perceive car weight, extinguish small blows from a carriageway and transfer the efforts arising at accelerations, braking and the movement on turns.
Wheels and tires are calculated on normal operation at loadings up to the recommended pressure parameters, maximum at observance, in tires.
Observance of these parameters, quality of adjustment, and also skills of driving exert impact on an operational cycle of the tire. Passing of abrupt turns at a high speed, sharp accelerations and intensive braking accelerate wear of tires.
Characteristics of modern tires – the sizes, sizes of external loadings, internal pressure and the maximum recommended speed of the movement – are standardized for ensuring interchangeability of tires at their operation.
Now on some types of cars all-weather radial tires with a steel breker are used as standard. These tires are intended for the movement on snow with the average force of adhesion, for 37% exceeding this indicator for earlier used seasonal tires. Other operational indicators, such as coupling of tires with a damp surface, resistance to swing, air resistance, are also a little improved. It is reached at the expense of more perfect design of a protector and improvement of the materials which are applied to its production.
Calibrating of tires for cars depending on degree of loadings
Now all cars of Daewoo are equipped with tires, calibrated depending on settlement operational loadings. These tires are calculated for two ranges of loadings: standard (240,8 kPa) and loaded (282,08 kPa). The majority of cars are equipped with tires for operation with standard loading.
As pressure unit of measure in tires serves the kilopascal (kPa). In literature pressure can be specified both in kilopascals, and in pounds per square inch (psi). One pound is per square inch equivalent to 6,88 kPa. The translation of units of pressure is given in table 14.1.
Table 14.1. Transfer of units of pressure measured in kilopascals (kPa) to pressure units measured in pounds per square inch (psi)
Instruction about pressure in tires
The instruction is located on inside of a door of the driver and contains information on tires. This information includes the maximum load of the car, the sizes of tires (including spare), and also pressure in cold tires (including spare).
Wheels and tires
Wheels have to be replaced if they are bent, have dents, an excessive radial or side beating, leak of air through welded seams, the increased openings under bolts if nuts of fastening of wheels densely do not drag on or when wheels strongly rusted. Wheels with the increased beating cause vibration of the car at its movement.
The rims made of steel or aluminum with rim sizes 5,5Jx14, intended for replacement have to be equivalent factory on a permissible load, diameter, rim width, shift and a configuration of fastening on the car. Installation of wheels with the non-optimal sizes and parameters differing from recommended exerts negative impact on wear of tires, cooling of brakes, calibration of the speedometer/odometer, clearance of the car, and also a gap between the tire and a body of the car.
Steel wheels are identified on two - or to the trigram code which is beaten out on a rim near the gate.
Aluminum wheels have to have a code and number of a detail, and also the identifier of the manufacturer cast on the back party of a wheel.
Install only radial tires on cars.
In radial tires of thread of a cord are located on the smallest way between tire boards. The Brekerny belt surrounds a thin and elastic framework and provides stability of the tire.
In tubeless tires the camera is replaced with the vulcanized inside layer with high air tightness. The board of such tire has to be established on a disk rim reliably and hermetically. Lack of the camera in the tire reduces the mass of a wheel and simplifies its installation on a disk rim.
Marking of tires is put on its sidewall. Tire width, its design and diameter of a rim of a disk make the minimum information necessary for marking of the tire.
Knowledge of marking of tires helps at their choice (fig. 14.1). Radial tires have the following marking, for example:
P185/65 R 14
Р – tire type;
Р – passenger;
N – temporary;
With – commercial.
185 – width of a profile of the tire, mm;
65 – tire profile height relation to its width h100.
This relation for tires of cars is ranging from 60 to 80. The relation equal 35 demonstrates that tires are intended for sports cars.
Irrespective of the size of this relation, one landing diameter of the tire is used. Nizkoprofilyy tires (with the small size of the relation of height of a profile of the tire to its width) provide high stability of the car at the movement on turns.
R – arrangement of threads of a cord;
R – radial;
In – diagonal;
D – with a diagonal cord;
14 – diameter of a rim of a disk, inch.
The data containing information on an identification code of the tire and date of its production, and also information on the maximum loading capacity and internal pressure are near DOT symbols on a tire sidewall.