Tyre

Tyres
Tyre is a cushion provided with an automobile wheel. Tyre is a band of layers of an iron, steel, rubber etc mounted on rim of a wheel and transmits the load and power to the road.
Functions of a tyre
To carry the load of vehicle and transmit it to road. To absorb the shocks caused by road irregularities and provide cushioning effect. To grip the vehicle with road thereby provide steering. To transmit driving and braking forces of vehicle to road. To provide cornering power for smooth steering.
Requirement of the tyre

a) It should be strong enough to transmit vehicle load to the road. b) It should be balanced both statically and dynamically. c) It should not wear away at surface after long usage. d) It should have adequate friction to roll on different types of road surface. e) It should be light in weight to reduce weight. f) It should be easily accessible for removing and mountings.
Desirable tyre properties:

a) b) c) d) e) f) g) Nonskidding Uniform wear Load carrying Cushioning Power consumption Tyre noise balancing
Construction of the tyre (May 08/ Dec 09)
1. 2. 3. 4.
Bead Plies Carcass Tread
5. Side wall
6. Ribs and grooves 7. breaker
Types of tyres (Dec 07/09/ May 09)

a) On the basis of construction
I. Conventional tubed tyre II. Tubeless tyre
b) On the basis of pressure and volume

I. High pressure tyre (pressure upto 4.2 kg/cm2) II. Conventional tyre (pressure in range 1.68 to 2.8 kg/cm2) III. Super cushion tyre (pressure in range 1.4 to 1.68 kg/cm2)
Conventional tubed tyre
Tubeless tyre (May 08/09)
Advantages of tubeless tyre

a) b) c) d) e) f) Improved safety Ease of puncture repair Slow leakage of air Simple assembly Better cooling Lesser unsprung weight
Disadvantages of tubeless tyre

a) Early replacement b) Difficult puncture detection c) cost
Tyre rating (Dec 07/09/ May 09)
Tyre selection (Dec08)

a) b) c) d) e) Width of the tyre Bead diameter Rolling radius Bead profile Carcass type
Factors affecting tyre life (Dec 09)

a) Inflation b) Vehicle maintenance
i. ii. iii. iv. Wheel alignment Camber and castor Brakes Steering linkages
c) Driving manners d) Miscellaneous factors

i. Overloading ii. Higher atmospheric temperature iii. Road conditions
Preventive maintenance of tyre (Dec 07/ May 09 )

a) b) c) d) e) f) g) h) Inflation pressure Keep oil and grease away Running on flat tyre Alignment of the wheel Cornering Braking Rim condition Spare wheel
Precautions regarding tyres

1. Check the tyre pressure once in a week. Do not measure tyre pressure immediately after driving when tyre is hot, as it will give wrong reading. 2. Ensure the valve cap is provided on the valve. The ca serves to prevent air leakage and prevents dirt and dust from getting inside the valve body. 3. In case of any puncture, do not drive vehicle. Jack up the vehicle and replace with stepny. 4. Inspect the tyre regularly for wear of tread pattern and side walls. 5. Overloading of vehicles should be restricted. 6. For uniform wearing of tyres, all wheels should be rotated after fixed intervals or as mentioned by manufacturer. 7. Ensure similar tyre fitted on both sides of the axle. 8. Smooth braking, slow speed turning , slow driving increases tyre life. 9. All the tyres should be equally loaded.
Wheel and tyre troubleshooting

1. Wheel bounce or tramp This is due to eccentricity of wheel and tyre. It is also due to incorrect tyre pressure. 2. Wheel wobble or shimmy. This may be due to wearing out of hub bearing, dynamic unbalance due to buckled wheel incorrectly fitted tyre, bent axle shaft. 3. Side wear of tyres. It is due to low tyre pressure. 4. One side wear of the tyre This may be due to incorrect camber angle or incorrect toe in or sagging axle. 5. Centre wear of tyre tread. This is due to high tyre pressure. 6. Uneven tyre wear. this is due to buckled wheel or wheel and tyre assembly is out of balance. 7. Tread cracking This is due to overloading
8.
Tread or ply separation This may be due to overloading, excessive or incorrect tyre pressure, high speed or impact. 9. Loss of pressure. small loss of pressure takes place regularly, it is not due to any defect but an account of normal diffusion of oxygen through the tube material. 10. Radial tyre lead. Lead is the tendency of the car to deviate from a straight path even when there is no pressure on the steering wheel. Lead is caused by incorrect alignment, uneven braking adjustment or some defect in tyre construction.
Carcass types
1. Cross ply or bias ply 2. Radial ply 3. Belted bias ply
Rear axle drive

The rear axle drive is subjected to following forces and torques
Weight of the vehicle Driving thrust Torque reaction Side thrust
Rear axle
Semifloating rear axle
Full floating rear axle
Three quarter floating rear axle

Tyre

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Tyre

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Tyres

Requirement of the tyre

Desirable tyre properties:

Construction of the tyre (May 08/ Dec 09)

Bead Plies Carcass Tread

Types of tyres (Dec 07/09/ May 09)

b) On the basis of pressure and volume

Conventional tubed tyre

Tubeless tyre (May 08/09)

Advantages of tubeless tyre

Disadvantages of tubeless tyre

Tyre rating (Dec 07/09/ May 09)

Tyre selection (Dec08)

Factors affecting tyre life (Dec 09)

c) Driving manners d) Miscellaneous factors

Preventive maintenance of tyre (Dec 07/ May 09 )

Precautions regarding tyres

Wheel and tyre troubleshooting

Rear axle drive

Weight of the vehicle Driving thrust Torque reaction Side thrust

Semifloating rear axle

Full floating rear axle

Three quarter floating rear axle

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