Automobile Tyres

ContentsTyre-functions & Properties.Tyre-Types Types of carcass(Tread)Comparison of radial & bias-ply

tyresTyre materials & Considerations in

tread designTyre designation & Factors

affecting tyre lifeTyre trouble shooting & Tyre

manufacturing

Tyre and its functionsTyre is a rubber member which

gives the cushion to the automobile. It consists of outer cover i.e. tyre proper and tube inside.

The tyre-tube assembly is mounted over the wheel rim and air inside the tube carries entire load and provides cushion.

Tyre cross-section

Functions of tyreTo support the vehicle load.To provide cushion against the shocks.

To transmit driving and braking forces to the road.

To provide cornering power for smooth steering.

Properties of tyresNon-skiddingUniform wearLoad-carryingCushioning Power consumptionTyre noiseBalancing

Types of tyresConventional tubed tyre.

Tubeless tyre.

Tubed tyre

Tubeless tyre

Advantages of tubeless tyres

Lesser unsprung weight.Better cooling.Lesser rolling resistance.Comfortable ride.Slower leakage of air.Simpler assembly.Improved safety.

Types of carcass(Tread)

Cross ply (or) bias ply type.Radial ply type.Belted bias ply type.

Cross ply (or) bias ply type.

Cross ply (or) bias ply type.

Radial ply type

Radial ply type.

Belted bias ply type

Comparison of radial and bias-ply tyres

Advantages of radial ply tyres:-The side walls can be bend readily ,its

shock absorbing capacity is 25% more than bias ply or cross ply.

The breaker strips of radial tyres act independently of the wall plies unlike in cross ply where there is no breaker strip.

Lower rolling resistance and hysteresis loss leads to less fuel consumption.

Longer tread life because of less heat build in tyre.

Breaking efficiency on wet roads is better because of greater sidewall flexibility and tread stiffness.

Smaller slip angles and higher cornering power which results in Better steering characteristics.

While taking turns it has less tendency to distort and lift off the road from one side.

Larger resistance to punctures ,cuts and impacts in the tread area.

Tyre materialsFor carcass:-At the time of second world war,

staple cotton was the tyre carcass material and it was replaced with rayon.

Then nylon was introduced which is stronger, more elastic and cooler running than rayon.

Then terylene was introduced.

For cords of stabilizer belts:-

Rayon ,Terylene ,glass fibre or steel.

Rubber :-Rubber used in tyres is blend of

natural and synthetic rubbers to which various chemicals are added to obtain desired properties like wear resistance ,reduced hysteresis, less internal friction.

Considerations in tread design

Grip

Noise

wear

Tyre designation

Factors affecting tyre life

Inflation

Vehicle maintenance

Manner of driving

Miscellaneous factors

Tyre trouble shootingSide wear of tyresOne side wear of tyresCentre wear of tyre treadUneven tyre wearUniform rapid wearRapid wear with feathered edges on

the treadTread crackingTread or ply separationLoss of tyre pressureRadial tyre leadRadial tyre waddle

Tyre manufacturing

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