Different outsoles are recommended for different kinds of surfaces and intended use. In outdoor shoes, the sole is designed specifically for walking on varying surfaces. Rubber is the most durable of the materials, but there are also big differences between rubbers: the softer, the more durable, but the harder, the more durable. It is important to find a golden middle, where the rubber is soft enough to give a good grip, but hard enough to last as long as possible. The same applies to shoe soles as to car tires, i.e. soft rubber wears out faster, and even faster at higher temperatures. Just like in tires, the pattern is also important in soles: in hiking shoes, the pattern is designed for loose and uneven terrain, and in running shoes for flat hard surfaces, etc.