What Is a Tread Void?

A tread void is the open space between tread blocks and ribs. These grooves and channels give water, slush and loose material somewhere to move as the tyre passes through the contact patch.

What Does Void Ratio Mean?

Void ratio describes the proportion of the tread area that is open space rather than solid rubber. A tyre with a low void ratio has more rubber in contact with the road, while a tyre with a higher void ratio has more open channels.

Low Void Ratio

A lower void ratio can provide a larger contact area on clean, dry roads and is commonly associated with road tyres designed for stable handling and good dry grip.

High Void Ratio

A higher void ratio gives more space for water, mud or snow to move through the tread. That can be useful for wet-weather, winter or off-road applications, although the exact performance depends on the complete tyre design rather than void ratio alone.

How Does It Affect Aquaplaning?

Open grooves help move water away from the footprint, which can support wet grip and reduce the risk of aquaplaning. Tread depth, tyre pressure, road speed and the depth of standing water are also important.

Why Tyres Use Different Patterns

Tyre designers balance void ratio with tread-block stiffness, noise, wear, wet grip and dry grip. That is why a performance road tyre, winter tyre and off-road tyre can look very different even when they are the same physical size.