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

The tread grooves pass air between the tyre and road surface, thereby preventing tyre from overheating
The crests between the tread grooves absorb road noise
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 positive crankcase ventilation (PCV) system is that it

Promotes combustion by creating a swirling movement in the air-fuel mixture
Feeds blow by gases to the exhaust manifold
Mixes fuel with air
Returns blow by gases from the crankcase to the intake system

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