The Technology of Tyre
I. Notice of Tyre Application
Main raw materials of tyre production are rubber and framework materials (such as nylon cord, steel cord, etc.). Different materials have different changes in characteristics while being heated. Different from other materials, nylon cord shrinks while being heated. High temperature also speeds up the aging process of rubber. Therefore,we say that the main reason for the damage of tyres is over high temperature of carcass.When discovering that the tyre temperature is too high, you must stop the car and cool down the tyre, because as soon as the carcass temperature is too high, the physical mechanical performance of rubber and cord and their adhesive force descend, the heat aging is accelerated,and separation easily happens to the crown, shoulder and sidewall of tyres. The impact from outside force also easily leads to burst of crown and shoulder of tyres.Therefore, during the application process, users should comply with Regulations on Tyre Application and Maintenance. While conducting first and second level maintenance to vehicles, users should also conduct first and second level maintenance to tyres.
(I) Inflation Pressure.
The tyre inflation should be carried out according to prescribed standard.
Both over-inflated and under-inflated tyres wear out more quickly.
Under-inflation engenders the following influences:
1. For under-inflated tyres, carcass deformation becomes more serious, and the tyre generates excessive heat, which can easily lead to ply separation of carcass, breakdown of cord, and burst of slips.
2. Excessive heat of tyre speed up the deterioration of inner tube.
3. In application of dual tyres, the neighboring sidewalls squeeze and rub with each other and easily damage. The under-inflation of one of the tyres increases the load of the other one, and speed up the deterioration.
4. While working in the condition of under-inflation, the cover easily moves on rim, which leads to fall-off of rubbing slips and valves of inner tube.
5. Under-inflation intensifies abnormal tread wear and reduces mileage. According to related materials, if the air pressure is 10% lower than standard pressure,the mileage of tyres decreases by about 12%; if the air pressure is 25% lower than standard pressure,the mileage of tyres decreases by about 30%.
(II) Load
Overload shortens the longevity of automobile parts and tyres, intensifies the deformation of tyre carcass, increase the contact area with the ground, and accelerate wearing out of tread and warming process of tyres, so as to lead to tyre damage quickly. Overload engenders the following influences to tyres:
1. Separation of carcass plies, separation between tread and breaker, and even final burst.
2. Crack of tread pattern.
3. Overload intensifies carcass deformation, and easily leads to break of cord and burst of slips.
4. Overload enlarges the deformed part of tyres, heats up carcass, and shortens tyre longevity. Overload by 10% shortens tyre longevity by about 20%. Overload also increases rolling resistance. Overload by 30% increases rolling resistance by about 45-60%.
(III) Running Speed
1. Different tyres have different speed limit. Excessive high-speed drive leads to early damage of tyres.
2. In case of uneven road surface, high-speed drive easily leads to impact of road barriers and tyre damage.
3. Carcass warms up quickly in high-speed drive, which leads to decline of many performances of tyres.
4. Tyres with high ply rating and heavy load are not suitable for high-speed drive.
II. Notice of Tyre Assembly
1. Tyres should be assembled on standard auto models and rims. One automobile should be assembled with tyres with the same brand, size, structure, pattern, and ply rating. Radial ply tyres can never be mixed assembled with diagonal tyres.
2. The tyre inflation should be carried out according to prescribed standard. Both over-inflated and under-inflated tyres wear out more quickly. Regular check and makeup of pressure is required, and guarantee the pressure is up to the standard. Long-term driving leads to warm-up of tyres, which follows with higher pressure, so you must stop the car and cool down the tyres. Deflation is prohibited.
3. Load of tyres cannot exceed standard load, and unbalanced load should be prevented.
4. You should check whether the rim is up to the standard while assembling the tyres. Damaged or deformed rims are prohibited. For tubeless rims, the air-tightness of valves should also be checked. Whiling changing new tubeless tyres, new valves should also replace the old ones at the same time.
III. Correct Tyre Application
1. Inflation Pressure: Keep tyres inflated to standard pressure. Properly raise the pressure for serious overload.
2. Load: Load of tyres cannot exceed standard load, and unbalanced load should be prevented.
3. Rotation: Conduct periodical rotation according to the standard method.
4. Vehicle Status: Adjust in time in case of any problems.
IV. Maintenance Knowledge of Tyre Application
1. Inflation Pressure
(1) Tyres should be inflated according to Form of Inflation Pressure and Corresponding Load prescribed in national standard.
(2) After inflation, you should check the leak resistance of all parts. In case of any leakage, timely repair is required.
(3) During the application process, the internal pressure of tyres must be normal. During long-term driving or operation, periodical check on tyre pressure should be conducted. Front and rear axles should be set up during long-term parking.
(4) Over-inflation easily leads to friction and burst of crown; Under-inflation easily deforms and wears out.
(5) In application of dual tyres, keep consistent pressure for the two tyres, and different pressures for two tyres are prohibited.
2. Load
(1) Load of tyres should be in accordance with the load prescribed in national standard. Overload is prohibited.
(2) Freights of the vehicle should be distributed evenly, and unbalanced load should be prevented.
(3) Serious overload leads to abnormal wearing of tread, shoulder separation, ply separation, burst of slips, etc.
(4) Tyres with high ply rating and heavy load are not suitable for high-speed drive.
(5) For strengthened tyres, load can be properly raised according to design standard.
3. Speed
(1) Different tyres have different speed limit. Excessive high-speed drive leads to early damage of tyres.
(2) In case of uneven road surface, high-speed drive is prohibited. Hard braking and sharp turn should be prevented, so as not to bump into other objects, especially acute ones.
(3) Carcass warms up quickly in high-speed drive. In case of excessive high temperature, timely measures (such as natural cool down by stopping the vehicle) should be carried out to prevent burst of carcass.
(4) Dynamic balance test, counterweight and revision must be conducted on high-speed tyre and vehicles.
4. Pattern
(1) Circumferential pattern is featured with small rolling resistance and high speed, suitable for hard road surface like cement and tarred road
(2) Transverse pattern is featured with strong gripping power and excellent climbing ability, suitable for present status of domestic common road surface.
(3) Dual purpose tread pattern has features of both circumferential pattern and transverse pattern, suitable for cement, tarred and slushy road surface.
(4) Cross-country tread pattern is suitable for roadless or road surface with poor condition.
(5) Tyres should be replaced when the tread pattern is worn to tread wear indicator.
5. Storage
(1) Tyres should be stored in warehouse to avoid sunshine and rain.
(2) Tyres should be far away from heat source, power generating equipment and locations generating ozone.
(3) Tyres cannot be stored together with oil, inflammables, and chemical corrosives.
(4) Tyres should be put upright. Flat lying, piling, or hanging through the tyre hole is prohibited.
(5) Tyres should be used according to the time of production and storage. The storage time cannot exceed three years.
6. Type Selection
(1) Radial ply tyre is suitable for high-speed vehicles. There are heavy duty truck radial ply tyre, light truck radial ply tyre, and passenger car radial ply tyre.
(2) Diagonal tyre is suitable for non- high-speed vehicles. There are heavy duty truck tyre, light truck tyre, and passenger car tyre.
(3) Agricultural tyre is suitable for all kinds of tractors and agricultural vehicles.
(4) Off-the-road tyre is suitable for all kinds of engineering machinery vehicles.
(5) Industrial vehicle tyre is suitable for all kinds of forklifts and special vehicles.
7. Vehicle Status
(1) Regular inspection and adjustment on front wheel and toe-in should be conducted; otherwise, partial wearing and early damage will happen to tyres.
(2) Rusty or deformed rims and rims with non-standard size are prohibited; otherwise, it will lead to friction of slips.