
A 29er studded tire is a highly specialized item, on two fronts. First, 29er tires in general are relatively unique and can be hard to find. Secondly, studded tires are usually only found at the best bike shops and are only used for certain types of seasonal riding.
A 29er studded tire is designed with one purpose in mind, riding in icy or snowy conditions. Just like a typical snow tire for a car, these tires incorporate studs designed to dig into the ice, providing a higher degree of traction. The studs can be made from any number of materials including steel and composites.
It is important to keep in mind that a 29er studded tire will not give you the ability to magically start, stop and turn at high speeds while riding on the ice. While they do offer a bit more traction, ice is still ice and as such a cyclist should be cautious when riding in these conditions. Slow and steady is much more effective than fast and aggressive with these tires.