Definition of Land Sea ratio

This term refers to the ratio of tread to grooves in a tyre’s contact patch. A tyre with wider grooves and heavy siping etc will have what is referred to as a high negative ratio i.e. less actual tread pattern contact with the road. A lower void ratio means more tread pattern in contact with the road, resulting in better dry handling. More tyre contact with the road means better handling and performance from increased energy transfer, which is why racing cars are fitted with slick tyres.

The ratio is worked out as follows:

Negative ratio = (Void Surface / Total Footprint Area) %

  • Better grip in dry conditions
  • Longer wear life
  • Better noise emissions

Advantages of higher negative ratio:

  • Better grip in wet conditions
  • Better hydroplaning resistance
  • Better rolling resistance
  • Better traction on loose terrain

Typical void ratios:

  • General touring tyres – 30%
  • High performance tyres – 35%
  • Ultra high performance tyres – 38%
  • Winter tyres – 40%
  • 4×4 tyres – 40%