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BIKE TECH: Mountain Bike Tire Pressure

The Chequamegon Fat Tire Festival's combination of high speed and sharp rocks can wreak havoc on mountain bike tires.

Just as mountain bikes have evolved, so too have mountain bike tires and the air pressure put into them.

Let's step back 20 years in time, when mountain bikes were more like road bikes. It was thought at the time that relatively high amounts of air pressure in a mountain bike tire would allow the bike to roll faster down the trail (as it generally does on the road). Well, since then, mountain bike trails have evolved from gravel roads and 3-wheeler trails to single track, often with rocks, features, and other technical elements. It is in part this change in our trails that has driven the evolution of the mountain bike as well as mountain bike tires.

Even lightweight xc mountain bike tires today are designed with these extreme terrain elements in mind and are more resistant to punctures, sidewall tears, and even pinch flats. Today's mountain bike tires are also designed such that there is much more air volume within the tire - often taller and wider than tires in the past. This allows riders to use less air pressure in a tire without risking a pinch flat. (A pinch flat is when a wheel runs over an abrupt bump and the tube gets pinched between the rim and the bump, creating a hole in the tube - thus a flat tire.)

Now, why would you want to run low pressure in your tires? Well, there are a few very good reasons:
  1. Less pressure means that the tire will absorb many small bumps and vibrations, smoothing the ride of the bike.
  2. Less pressure means the tire will be "softer" and conform more to the surface you're riding on. This means better grip and traction.
  3. Less pressure means that the tire will "roll through" bumps in the trail, rather than bouncing over then. This is faster and more comfortable.
The key with running relatively low pressure is to find that sweet spot between not enough and too much. This number can change significantly based on the specific tire you're using, your weight, your riding style, if you're riding a 26" or 29" mountain bike, or even the trail you're riding.

Tires do have pressure recommendation ranges printed on their sidewalls, but following are some very general recommendations for 2" wide cross country mountain bike tires (such as the WTB Nano Raptor, Hutchinson Python, and many others) that we've found works out optimally for Midwest riding:

Front Wheel on a 26" MTB: 30psi
Rear Wheel on a 26" MTB: 33psi

Front Wheel on a 29" MTB: 28psi
Rear Wheel on a 29" MTB: 30psi

Now go check your tire pressure (as changing a flat is rarely a good time) and ride!

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