Sipes
These are the small, slit-like grooves in the tread blocks that allow the blocks to flex. Sipes are particularly helpful on ice, light snow and loose dirt.
Grooves
Create voids for better water channeling on wet road surfaces. Grooves are the most efficient way of channeling water from in front of the tyres to behind it
Blocks
These are the segments that make up the majority of a tyre's tread. Their main function is to provide traction.
Ribs
The straight lined row of blocks that create a constant circumferential contact.
Dimples
These are usually towards the outer edge of the tyre. They improve cooling.
Shoulders
Provide continuous contact with the road while cornering, wrapping over the inner and outer sidewall of a tyre.
The Void Ratio
A low void ratio means a tyre has more rubber is in contact with the road. A high void ratio increases the ability to drain water.