Trails nowadays are nothing like they used to be, very little pedaling and/or braking and the dirt is usually rock hard, it doesn't make sense to mimic MX tires (that have to accelerate, brake and turn in soft dirt) with big knobs anymore and BF rides a mix of everything, so his tire needs to work well on everything. That lead to giving the FT1 a relatively smooth center section, to make the tire fast. Turning is when an increase in grip (instead of outright speed) is needed, lean the bike over in a turn and the micro-knobs come into play. The micro-knobs provide a perfect balance of surface area, stability and space in between for when the dirt might be a little soft still. The micro-knobs actually stick up above the main surface a super small amount, this allows them to sink into that slightly soft dirt and give an increase in surface area contact, but the amount they are raised doesn't negatively affect stability or grip on hard surfaces. At the edges of the tread pattern are smooth tread blocks that help protect the sidewall on ramps and street. 20 x 2.25 and 20 x 2.35