Mountain Bike Tire Pressure: Everything You Need to Know
Is There an Ideal Mountain Bike Tire Pressure for Everyone?
Wouldn’t life be easy if there were a tire pressure that worked for every rider? Unfortunately, like most topics we cover on this blog, things are more complicated than that. Ultimately, what we want out of a tire pressure setting is a balance between maximum traction and a smooth ride while also being fast and preventing damage to the tire and rim. Run too much pressure – you’ll have a rough ride and lack traction when you need it. Run the pressure a little too low and you will deal with increased rolling resistance and run the risk of damaging a wheel when hitting roots and rocks. Read below to learn a little about the factors affecting tire pressure and how to determine the correct pressure for your ride.
Factors that Affect MTB Tire Pressure
There are many factors that affect the ideal pressure for your ride. Although this isn’t an exhaustive list, we have tried to cover the main points so you can begin to experiment and make informed decisions when airing up your tires.
If you’ve spent much time riding in groups, you’ve likely noticed that some riders are graceful and float over rough terrain while others seem to just slam into everything. If you’re the type of rider who is light on the pedals or tends to ride around rough terrain, you can likely run 2-3 psi less. If you’re a little less careful and tend to ride “heavy” pedaling hard through rough stuff then you will need to factor in puncture protection and add pressure.
In rough terrain tire pressure needs to be increased to prevent tire and/or rim damage. The danger is in hitting something hard enough to compress the tire to the point where the rim makes contact with the rock, root, or the ground. This can lead to damaging the tire as it is pinched or even denting the rim.
As speeds increase you’ll likely need to increase tire pressure slightly to reduce the chance of damage. This always needs to be balanced with maintaining traction. When trail conditions are perfect and speeds are high on a smooth surface, you can maybe get away with a higher pressure and a fast ride while still getting good traction. If traction is at a premium because the trail is wet or dry to the point of being dusty or if there is sand to deal with, you can decrease tire pressure. In these conditions you’re looking for maximum traction and speeds will be lower so there will be less risk of pinching the tire on the rim.
Weight of the Rider
Rider weight is the biggest factor affecting tire pressure. As a general rule, light riders will need much lower pressure while heavier riders will need to pump their tires up significantly higher. Again, the main concern is preventing a ride-ending mechanical due to pinching the tire or damaging the rim on a big hit. As heavy riders will compress the tire more and create much more force going over obstacles, they will run higher pressure.
Tire and Rim Size
Tire size can greatly affect the pressure you choose to run. As tire size, and therefore volume, increases pressure can be decreased. Without going into the physics of it, a large tire will resist the unstable feeling of the tire squirming at lower pressure. Since the volume is larger, you also run less risk of an impact causing damage.
We recommend you match the tire size to the rim width. Using a wide tire on a narrow rim can feel less stable as the tire becomes more round and shaped like a balloon. The tire will feel like it wants to flex and will not be confidence inspiring at lower pressure. Conversely, if the tire is too narrow for the rim, it becomes more square shaped and will not feel consistent when leaned over in a corner.
XC wheels will usually be around 25mm and work best with tires 2.3” and under. Wheels around 28mm are great for all-around trail riding and work best with tires up to 2.6”. If you’re looking to use a tire wider than 2.6” then we recommend wheels with a width above 32mm. This relates to tire pressure because as wider rims and tires will allow lower air pressure.
Tubes or Tubeless
Tubeless tires are the preferred choice out on the trail as it provides better rolling resistance and increased flat protection at lower pressures. If you’re still using tubes, you will need to use much higher pressure to prevent pinching the tube against the rim. Look at the tire that came on your bike and use the recommendations printed on the sidewall. With inner tubes, this is likely still over 30-40 psi for even light riders. Running tubeless these riders can be in the low 20’s and maybe even in the teens in some conditions. Tubeless is definitely the way to go!
Mountain Bike Tire Pressure Chart
There are many online pressure calculators you can use to determine a good starting point. You can start by using SRAM’s guide here.
Stan’s also has a simple recommendation: Take the rider’s weight in pounds and divide by 7. Subtract 1 from that number for the front and add 2 for the rear. I’m 160 pounds so 160/7= ~23. I would run 22 psi in the front and 25 in the rear. This would be a starting point that I could change based on tire size and conditions.
Notice that you will likely use less pressure in the front tire as you have less weight on the front and will want maximum traction in corners. You will use a little higher pressure in the rear tire to help prevent hitting the rim on the tire and decrease rolling resistance on the rear wheel as it carries more weight.
How to Find Your Ideal Mountain Bike Pressure
Your ideal mountain bike pressure will ultimately depend on all of the variables above and what you want the ride to feel like. This requires testing. Geeking out and trying to perfect your setup is part of the fun of mountain biking!
Go for a ride at the recommended pressure from a calculator or from doing the math above. If you are not bottoming out against the rim on big hits but you feel like you aren’t getting enough traction, decrease the pressure slightly. We recommend 1-2 psi at a time. If the tire feels unstable (as if it’s rolling around on the rim) in corners and you’re hitting the rim against rocks and roots, increase the pressure. While low pressure is more comfortable and will provide better grip, you need to weigh the importance of preventing flats and mechanical issues.
How to Know When You’ve Found the Right MTB Tire Pressure
Tire pressure is always going to be a give and take, and you’ll likely always be sacrificing something in a part of the course. With some testing and thought into what you want out of your setup, you’ll find a sweet spot that works for you in most situations to provide the best ride over most of the terrain you plan to cover.
If you’re racing XC and you feel like you have 100% traction but you need to be careful on one obstacle on the course so as not to damage the wheel, that may be a good trade-off. If you’re out in the desert alone, you likely won’t like the risk of running pressure that is too low. You’ll know when you have the right tire pressure when you’re comfortable and confident in navigating the trail while also being able to tackle the tough parts without feeling that unnerving feeling of the rim making contact with an obstacle. Spend a little time finding the optimal tire pressure for you, and your ride will be much more enjoyable.
Feel free to browse our website for the tools and tires you need to find the perfect tire set up for you. We offer a wide selection of tires, pumps, and everything you need to find the optimal pressure for your next ride!
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