Automobile Engineering in ME
The main function of the tread pattern on tyre is that

The crests between the tread grooves absorb road noise
The tread grooves pass air between the tyre and road surface, thereby preventing tyre from overheating
In wet conditions, the tread grooves expel water that is drawn between the tyre and road surface
The tread pattern protects the tyre's inner carcass from small stones and pieces of glass

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Automobile Engineering in ME
The function of a first compression ring (top ring) is that it

Maintains a seal and prevents the fuel leakage
Creates swirl
Maintains a seal and prevents escape of burned gases and loss of pressure in the combustion chamber
Increases the combustion temperature

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