Mountain bike tire guide. Mountain bikes by nature are bikes designed to go off road on roads ranging from flat gravel roads to extreme off road trails with rocks and drops. The tires need to be rugged, large, and have enough traction. Depending on your needs the tires may vary slightly.
Most mountain bike tires come in standard 26 inch size tires. Smaller bikes may have 24 inch tires and 29 inch tires are available but less common. You should stick to the size that your bike came with and if you are building a custom bike make sure the tires fit within the fork and dropouts.
Width is another dimension considered. The more extreme the terrain the wider the tire you’ll want. Casual riders or road riders may want to go with smaller tires under 2.10 inches. Most users will find 2.20 to 2.30 inch tires to be sufficient for off road use. Some tire makers go as high as 2.5 inches with some going slightly wider but these tires may not fit on most mountain bike frames.
Most tires for mountain bikes will be double walled but not all. Double walled tires are important to protect against punctures and tears in the tire. Rocks, tree roots, and debris pose a hazard to tires.
Often referred to as tire “knobbiness” the traction is crucial for all bikes but could mean the difference between crashing and staying on the trail for mountain bikers. The knobbier the tire the greater the traction in most cases.
If you plan on riding in mud you want large knobby tires to keep the mud moving through the treads and not gunking up the traction. The greater the space between the large knobs the better the tires are for mud.
If you plan on riding on rocks, dirt trails, and gravel you’ll want knobby tires although they need not be as knobby as mud tires. The tire knobs can be shorter and closer together than mud tires.
In both muddy and dry trail conditions you’ll want to consider tires with traction knobs that go over the edges of the tire. These will help with handling especially in tight corners.
A trade off here is comfort for better control. On roads and sidewalks overly knobby tires will ride rough and almost bouncy. If you won’t be going off road and ride on the streets, comfort may trump off road control.
Always wear a helmet and consider additional protection if you do downhill riding or extreme terrain riding. Never exceed the listed tire pressure on the tires.
Many mountain bikers tend to “run low pressure” to increase the surface area of tire touching the ground. This can increase the risk of pinch flats but increase traction. On average 30 PSI seems to be a good “run low pressure” number, too much lower and pinch flats increase. Too high and the bike will bounce around.