WHAT DOES THE TIRE TREAD DO?
On a normal, smooth road, the tread has only limited influence on the riding properties. The grip generated by the tire on the road is almost exclusively the result of the rubber compound.
Off road though, the tread is very important.
In this situation the tread establishes an interlocking cog-like connection with the ground and enables the transmission of all driving, braking and steering forces. On rough or dirty roads, the tread can also contribute to better control.
WHY RIDE A SLICK TIRE?
On a normal, smooth road, even in wet conditions, a slick tire actually provides better grip than a tire with a tread, because the contact area is larger.
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WHAT DO THE DIRECTION ARROWS MEAN?
Most Schwalbe tire sidewalls are marked with a "ROTATION" arrow, which indicates the recommended rolling direction. When in use, the tire should run in the direction of the arrow. Older tires have the marking “DRIVE”, but it has the same meaning.
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WHY ARE SO MANY TREADS DIRECTION DEPENDANT?
In the case of a road tire the rolling direction is mainly important for aesthetic considerations. Tires marked with arrows simply look more dynamic.
There are also treads without a specified rotating direction.