MTB Tire Pressure
Calculator.
Dial in front and rear PSI for your mountain bike. Enter your weight, tire width, wheel size, setup and terrain to get a starting pressure and a safe working range.
Results update as you type. Start here, then adjust 1 psi at a time. If the tire squirms in corners go up, if you are bouncing off roots go down.
How the calculator works
Tire pressure is really about how much air volume you have supporting how much weight. Wide tires hold far more air at the same pressure, which is why a 2.6 inch tire runs several psi lower than a 2.0 for the same rider.
Use a proper low-pressure digital gauge. Most floor pump gauges are wildly inaccurate below 30 psi, which is the whole range that matters on a mountain bike.
MTB tire pressure FAQ
Most trail riders on 29 x 2.4 inch tubeless tires land between 18 and 26 psi, with the rear 2 to 3 psi higher than the front. Narrower or tubed tires need more, wide plus-size tires need less. Rider weight is the single biggest factor, which is why a generic number on the sidewall is close to useless.
Your body weight sits behind the middle of the bike, so the rear tire carries roughly 55 to 60% of the total load. It also takes the harder hits when you cannot unweight it. Running the rear a couple of psi higher protects the rim, while keeping the front softer gives you the grip and confidence you want when cornering.
Lower pressure means a bigger contact patch, more grip and a smoother ride, up to a point. Go too low and the tire squirms in corners, burps air off the rim, and you start denting rims on rocks. The right pressure is the lowest you can run without those symptoms on your usual trails.
Tubeless typically lets you drop 2 to 4 psi compared with an inner tube, because there is no tube to pinch flat. Adding a foam insert like a Cushcore lets you go 2 psi lower again and protects the rim, which is why enduro and downhill racers run pressures in the mid teens.
Air pressure drops roughly 1 psi for every 10°C (18°F) fall in temperature, so a tire set in a warm garage will read low on a cold morning trailhead. Altitude matters less for the gauge reading but a long descent heats the tire and raises pressure. Always set pressure at the trailhead, not at home.
Yes, drop 1 to 2 psi in the wet. The lower pressure lets the tread conform to slick roots and rock, which buys real grip. Keep an eye on rim strikes, since wet trails often mean the same rocks are still there under the mud.