Turn over your favourite hiking boot or trail running shoe and you are likely to see one of a handful of brands named on the sole. They are likely to include Vibram, Michelin, Continental, so own-brands such as those made my inov8 and Keen.
These brands use rubber, derived from tropical plants, or natural gas and petroleum, to form a durable, elastic and grippy surface on the base of outdoors footwear. Some add their own extra ingredients, such as invo8's graphene.
