Why Do Climbing Shoes Have No Tread?

The bottom of rock climbing shoes are typically made out of hard rubber. Rubber deforms into the shape of whatever its being pressed into, in this case the rock, thus increase the surface area of contact and allowing for extra friction.

In cars you will notice the rubber tires have tread, this is to allow any possible fluids such as water to be displaced somewhere, otherwise the water could get trapped and make the car slide much more. In rock climbing shoes no tread is used as typically they are meant to be used on rock faces where there is no water, and there is also the added benefit of having extra surface area due to no tread.

The effectiveness of rubber varies based off temperature. Rubber will deform more as the temperature rises. For rock climbing you typically want cooler temperatures as the rubber will remain harder and deform less yet still grip well.