TREAD FEATURES

Side knobs

Most tyres have a more pronounced shoulder tread, for improved cornering grip. With some designs, there’s a noticeable transition between the centre tread and side knobs as you lean the tyre over in a corner, which can lead to loss of grip.

Knob size

Bigger and more aggressively-shaped tread blocks generate more mechanical grip, but can make the steering feel vague and your bike roll slower on hardpack. Mud tyres, sometimes referred to as ‘spikes’, are covered with tall tread blocks designed to bite into soft terrain. At the other end of the scale, XC tyres have low-profile centre knobs to reduce rolling resistance, at the sacrifice of some grip, particularly under braking.

Tread gaps

Tyres designed to work well in wet conditions have large, consistent gaps in between the knobs. This allows mud to escape so the tread doesn’t get clogged up and the tyre can continue to grip.

Knob arrangement

Generally, tread blocks aligned side-by-side are designed for braking traction, while those aligned front-to-back are for grip in the turns. Shoulder tread is usually fore-aft for cornering, while centre tread is often aligned laterally for braking and pedalling.

Ramped tread

Many tyres have ramped centre tread blocks. The leading edge, which contacts the ground first, is tapered to smoothen the transition and so reduce rolling resistance, while the trailing edge is square, to maximise braking grip. These ramps mean the tyre must be mounted the right way around on the rim.

Siping

‘Siped’ tread blocks have a slit (or slits) cut into them that allows the rubber to splay out when pressed onto hard surfaces. This increases the amount of surface area in contact with the ground and provides edges to ‘key’ into tiny imperfections in rocks and roots, and so improves grip, particularly in the wet. Some brands vary the shape of the siping across the tread.