A mountain bike tire tread pattern is an engineering document. Every element is intentional. Center knobs handle straight-line rolling and braking. They're typically ramped on the leading edge to reduce rolling resistance and squared on the trailing edge for braking bite. Side knobs take over in corners, so they're taller, more upright, and often siped to deform and grip under lateral load. Knob spacing determines self-cleaning ability: tightly spaced knobs pack with mud; widely spaced knobs shed it. Knob height sets the depth of bite. Tall knobs penetrate loose terrain, short knobs maximize contact on firm surfaces.