Mountain bike tires are built to perform multiple functions over varied terrain, and with a range of knob thicknesses and configurations, there's a mountain bike tire for every off-road situation. They are made to maintain traction on steep inclines or rapid descents, whether they are on wet leaves, dry dirt or mud. Also, mountain bike tires are built to withstand hard knocks from trail obstacles and sudden drops without going flat and leaving their rider stranded.
The most notable feature on a mountain bike tire is its aggressive appearance. Often thicker than road bike tires with rubber knobs jutting out from the tire, mountain bike tires maximize durability and traction on rugged trails. More contact with the ground and deep lugs make a mountain bike tire less likely to spin while ascending a hill on slick or loose ground. Also, sidewall treads are effective in preventing a bicycle from sliding out on fast turns.
Riders don't want to end up somewhere in the woods with a flat tire, so mountain bike tires must withstand extreme situations, from sharp rocks and thorns to bone-jarring drops. Most mountain bike tires feature thick rubber walls, but it takes more than a thicker sidewall for a mountain bike tire to survive a trek in the wild. The best mountain bike tires feature fabric casings lined with nylon and other materials, such as Kevlar, to increase their puncture resistance.
Mountain bike tires are subject to a myriad of conditions, and adjusting the tire's inflation will go a long way toward improving the tire's lifespan, as well as its performance. For off-road riding, the ideal pressure in a mountain bike tire is between 35 and 45psi, but conditions may dictate higher or lower pressure. On particularly rocky trails, higher pressure will help prevent flats, and on loose or slick terrain, lower pressure will help maximize traction.
The type of mountain bike tire you use will vary depending on the season and on what type of terrain you cover--some tires work well in wet terrain but wear out quickly on dry ground, and some tires that work well in mud aren't ideal for packed dirt. Many mountain bikers have several different sets of tires for differing conditions and terrain in their area. As you ride, try different tires to see which ones work best for your region and for the way that you ride.