
29er tires follow up on the logic of mountain bike wheels and tires and further emphasize tires that provide relief against all kinds of terrain. In particular, 29ers are meant to not sink in soft conditions such as mud or sand.
The term 29er is actually a little misleading. The diameter of most of these rims is about 24.5 to 25 inches, with the average 29er bike tire having an outside diameter of about 28.5 inches. Nevertheless, this is wider than standard mountain bike wheels and tires.
Advantages of 29er tires include an increased ease at moving over obstacles such as rocks, less of a tendency to sink in soft materials, improved straight line and cornering traction, and improved ground clearance. The longer spokes and rim also result in a wheel that is more flexible laterally.