The little rubber hairs on tires are called vent spews, sprue nubs, tyre nibs, gate marks, or nippers, and they are a byproduct of the tire manufacturing process. During the manufacturing process, rubber is injected into a tire mold, and air pressure is used to spread the rubber into all the nooks and crannies of the mold. In order for the rubber to completely fill the mold, small pockets of air need to be able to escape. There are small vent holes in the mold so trapped air can find a way out. When the air pressure forces the liquid rubber into all the orifices, a tiny bit of rubber makes its way out of the vent holes as well. These rubber bits firm up and remain attached to the tire when its removed from the tire mold. The little rubber hairs play no role in the tires performance, but they are an indication that a tire is new. Over time, they will eventually wear off due to environmental effects.