A Guide to Mountain Bike Tire Pressure
Not sure how much air your tires need? Cycling Expert Matt Guzman runs you through all of the factors you need to consider to find your perfect tire pressure.
How much air should I put in my tires? This is a question that seems amateur at face value, yet if you check the internet forums and comment sections for information regarding mountain bike setups, you'll quickly find that this is a hotly debated topic. There are many variables to consider when deciding what the right tire pressure is for you.
Generally, modern tires and rims (usually set up tubeless — more on that later in this article) can be run in the 18–29 PSI range, although there are reasons to air your tires even higher or lower. When someone asks me what pressure they should run their tires at, I don’t usually have a straight answer. Instead, I have a few questions to help guide them to the right pressure range. These questions below can serve as your guide to finding the perfect tire pressure.
1. Where & What Are You Riding?
This can be asked in several different ways. If you’ve ridden or hiked your local trails already, think of the terrain. Was the dirt on the single track soft or hard? Dusty or grippy? Are the trails laden with bumps, rock gardens, and/or roots, or are they relatively smooth? Do you need all the traction you can get from a softer tire, or are the trails fast and grippy enough to benefit from higher pressures? Knowing this is half the battle, since the type of bike you’re on will have different effects on different types of terrain.
XC racers might favor lower pressures to get up climbs with more grip, whereas more gravity-oriented riders will prefer higher pressures that keep the casing from folding when hitting berms and rock gardens hard. Freeride riders will generally ride at the highest pressures, as their tires need all the support possible when riding off of big drops. Enduro and downhill (DH) riders (especially racers) will often try to eke out a bit more grip and experiment with lower pressures.
2. How Much Weight Are You Putting on the Tires?
Mountain biking is a constant game of weighting the bike in order to get the most grip but without weighting it so much that the bike washes out. Usually, riders put lower tire pressure in the front, as you don’t ride with as much of your weight on the front all the time. This also will help with cornering traction; it is always preferable to have the rear tire brake traction before the front because riders are more likely to recover the bike if only the rear wheel is drifting.
Rider weight, of course, will have a significant impact on preferred pressure. Lighter riders generally will favor lower pressures than heavier riders due to their sidewalls being less likely to fold under hard cornering or braking.
3. What Is Your Tire & Wheel Setup?
This is a two-part question, with the first part being “How wide are your tires and rims?” Generally speaking, wider-diameter tires can be run at lower pressures. This is also true if you ride with wider rims, as that increases the overall volume of the tire. Wider rims also support the sidewall of the tire better, giving them more stability at low pressures. If your bike has narrow rims, and you want to add a bit of plushness to your ride but can’t run your tires low enough, you might consider changing to wider rims — granted that you’re okay with the extra weight and your bike can accommodate the extra rim width and tire volume. Dirt-jump mountain bikes will almost always require the hardest pressures, as riders in this category prefer tubes for simplicity on the hardest surfaces. If you have a dirt jump bike with good quality tires, it is safe to run a few psi less than the maximum recommended pressure for best results.
The next part is “How are your tires inflated and supported?” There are many variables here that will affect what PSI you prefer your tires to run at. Most riders on modern bikes have tubeless systems. Many are also using some kind of foam insert between their tire and rim. Both of these systems allow for less pressure in the tires because with tubeless tires there are no inner tubes at risk of getting a pinch flat. Riders using tire inserts may run at even lower pressures since the rims are protected from harsh impacts. Different tire casings will also require more or less pressure. Lightweight casing tires will often need more PSI for support, while heavier casing tires can be run at lower pressures without the risk of deforming.
4. What Does the Tire and/or Bicycle Manufacturer Say to Run Them At?
If you look at the logo printed on your tire, you will usually see a minimum-to-maximum pressure range also written on the tire. This can be a bit confusing because tire manufacturers aren’t necessarily printing their recommendations. Instead, the range printed on the tire is usually the tire’s limitations. A rider will rarely need to use pressures near the max range, and with modern tubeless setups, many riders use pressures lower than the recommended minimum.
For more reliable guidance, the tire and/or bicycle manufacturer might have a recommended tire pressure calculator on their website. If you can’t find any guides from the manufacturers of the tires or bike you use, there are always third-party calculators such as the one found on Bikefaff.
5. What Is Your Experience Level?
Beginners usually ride at lower speeds, meaning they can benefit from lower tire pressures, as they often don’t push the tire hard enough in the corners to deform it. It will also provide more comfort over rough terrain to run at lower pressures as a beginner. With experience, riders will develop personal preferences while they adopt a particular riding style. Riding at higher speeds will usually prefer higher pressures, since the rims can take on more damage from running too soft of a tire at speed. Most still want the tire to be soft enough to add comfort and grip to the ride, and some will even resort to tire inserts to get that combination.
Now that you’ve considered all the variables in the questions outlined above, where do you go from there? When I set up a new bike, I usually start with a manufacturer or third-party calculator based on my weight (remember to include your gear when factoring in your riding weight for better accuracy). From there, I’ll start riding at a trail that I am comfortable and familiar with, preferably one where it is possible to get laps in on a section of a trail. I’ll use these laps to perform a better/same/worse test. Whether you’re setting up a new bike or dialing in your trusted whip, you can use this same test for just about everything on the bike (tires, suspension, fit, etc.), but we’ll just focus on tires for this article.
- Ride a lap. If you’re more of an XC or all-mountain rider, make sure your loop involves a climb as well as a descent. For more gravity-oriented riders, a bike park or a downhill section with a return trail will be most preferred.
- If your tires felt slow or sluggish over the trail, add 1–2 PSI. If you felt like you needed more grip, let out 1 or 2 PSI. It is important to make incremental changes, as it will be easier to find a “sweet spot.” You might prefer to use a tire gauge for more accuracy, but most pumps’ gauges work well enough.
- Ride another lap. Pay attention to the bike’s performance after the changes you made. Does it feel better, worse, or the same?
- If it feels better or the same, keep adding or letting out 1 or 2 PSI at a time until it feels worse.
- If it feels worse after adding air, let that same amount out until it feels better again.
- If it feels worse after letting air out, then add that same amount until the bike handles better again.
If all of this sounds too tedious, don’t worry — there are simpler ways of choosing the right tire pressure. Make friends with riders on your local trails. They will be happy to give you advice, and they already know the trails! See if there is a social media group for your local trail network, and reach out for advice. Some riders also stick to what is recommended by the bike or tire manufacturer, and they gain favorable results.
The good/better/same test is really a tool for riders who want to be more precise with their setups and gain a deeper understanding of their bike. This doesn’t mean that more casual riders who don’t have extra time for this testing won’t ever find what works for them. Fortunately, modern mountain bikes handle very well, and your pressures don’t have to be within 1 or 2 PSI of accuracy to have a good time! Many riders adopt a set-it-and-forget-it attitude where they find what feels good and leave it be.
Let this guide serve as a roadmap to being more conscious of not just how much air is in your tires but of your bike’s overall setup, how it handles on the trails you ride, and ultimately your personal style as a rider. Will you be the rider who likes to tinker with their bike as much as they like to ride it? Or the rider who prefers to set their bike up once and forget about it to focus on the ride? Either way, happy trails!
Don’t forget to reach out to a Cycling Expert here to help you get all your other cycling questions answered as you shop for the perfect mountain bike.