No tire? No problem! — That’s a hell of a strong rim!
Some contend that the distinction between an extreme sport and a conventional one has as much to do with marketing as with the level of danger involved or the adrenaline generated. For example, ATV Rider is both dangerous and adrenaline-inducing but is not considered an extreme sport. One common aspect of an extreme sport is a counter-cultural aura - a rejection of authority and of the status quo.