Nowadays, tyres and cars are very sophisticated. Drivers are at risk of forgetting that the tyres are a car's one and only point of contact with the ground and that as a result they need to perform a certain number of functions such as steering,, carrying the load,, cushioning,, rolling,, transmitting drive, , lasting..
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Steering
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The tyres should steer the vehicle with precision, irrespective of the state of the surface and / or climatic conditions. The stability of a vehicle's path depends on the tyre's holding their course. A tyre must stand up to transversal forces without drifting from its path. In general, each vehicle has a particular inflation pressure per axle. Respecting pressure variations between front and rear ensures ideal directional stability. |
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Carrying
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Tyres support a vehicle not only when it is moving, but also when it is standing still and they must be able to resist considerable load transfers during acceleration and braking. A car tyre carrys more than 50 times its own weight.
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Cushioning
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Tyres absorb the shocks due to obstacles and cushions the vehicle from other irregularities in the road, ensuring driver and passenger comfort as well as contributing to the lifespan of the vehicle.
The main characteristic of a tyre is its great suppleness, particularly vertically. The great elasticity of the air contained in a tyre enables it to take deformation inflicted on it by obstacles and surface roughness. The correct tyre pressure, then, gives good levels of comfort whilst retaining good steering capacity.
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Rolling
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Tyres roll more evenly, more surely, with less rolling resistance for greater driving pleasure and better fuel consumption.
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Transmitting drive
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Tyres transmit drive : the engine's usable power, braking effort. The quality of the few square inches in contact with the ground dictates the level of transmission of drive etc.
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Lasting
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Tyres last in other words, keep to their optimum performance level for millions of wheel revolutions. The wear on a tyre is of course dependent on its conditions of use, (load, speed, state of road surface, state of vehicle, driving style etc), but also, to a large extent, on the quality of its contact with the ground. Pressure, therefore, has a major role to play.
It acts on:
- the size and shape of the contact patch,
- the distribution of stresses on the different points of the tyre in contact with the ground.
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These 6 functions guarantee safety, comfort and economy.
They are provided during the entire lifetime of a tyre, but elementary precautions for use must be taken by the user.
A tyre needs air to work and last.
So it is vital to check tyre pressures regularly. In fact, a tyre loses its precious air, molecule by molecule, because of the natural (very slight) porosity of rubber. To this are often added accidental causes such as valves or rims no longer being completely airtight, small perforations in a tyre etc.
Pressure dictates all a tyre's functions: functions of safety, economy and comfort and incorrect pressure erodes all these functions. A quick, regular check will greatly reduce this area of concern for the driver.
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