Riding your mountain bike with the appropriate amount of tire pressure can make a huge difference in how much control you have over your bike.
Setting your tire pressure too high will make for poor contact with the ground and also make your bike less controllable. Setting your tire pressure too low will make your tires unpredictable and also make them susceptible to pinch flats.
The appropriate amount of tire pressure in a mountain bike will vary between rider to rider and tire setup to tire setup. The conditions of your trail and the type of terrain your riding will also greatly impact what tire pressure you should be using in your tires.
The trick here is to find out exactly what mountain bike tire pressure works for you and your setup during normal conditions. After doing this, you can learn to adjust your pressure for different trails and types of terrain as needed.
You should start by finding a reliable pressure gauge or a pump with a pressure gauge. Then, use this same gauge or pump anytime you are making adjustments. A gauge can be very inaccurate, so if you switch around it you can make things much more difficult.
You should start with a higher pressure of around 40 -50 psi. If you have a tubeless system, you should start lower, 30 – 40 psi. The more you weigh, the higher pressure you should start with. Try this pressure for a while and get a feel for how the tires take corners and loose dirt.
Drop the pressure by 5 psi in each tire and get a feel for how this new setup rides and how it compares to your previous setting. You should notice some improvement in stability, and if you don’t, drop the pressure by another 5 psi.
You want to find the lowest pressure you can ride with without sacrificing pinch flat resistance. A pinch flat occurs when your tire rolls over an object then compresses to the point where the tire and the tube get pinched between the object and the rim on the wheel.
With tubeless tire systems, you can run much lower air pressure, as you don’t have to worry about getting pinch flats. If you start to dent your rims, burp air out along the bead, or feel the tire roll under the rim during hard cornering, you’ve taken the pressure much too low.