Tire Pressure Guide For Mountain Bikes

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When I first started riding my bike off-road as a kid, I quickly noticed that my bald street tires didn’t grip very well on the loose dirt of the trails near my house. I had the tire pressure filled up to about 50 psi and boy could I skid on those babies!

I’ve since learned that those two tiny rubber patches are the only things connecting you and your bike to the earth and as such, play a critical role in how your bike performs. So before you go drop your next bonus on some fancy new drive train or high-tech wheels that will save you .05 grams, consider some simple adjustments to your tire pressure and you may notice incredible control and performance gains without dropping a dime.

Not only will dialing in your tire pressure give you better performance, but it will also lead to fewer flats and increased efficiency, better control, and more fun on the trail. Read on to learn exactly how to set and keep the magic tire pressure that will give you permagrin without blowing the bank.

Tire pressure is subjective – there’s no one magic number

So let’s get this out right up front. Just like your favorite pair of shoes, the ideal tire pressure varies from person to person. It depends on riding style, technique, terrain, weight, and other factors. What’s perfect for one, will feel like crap for others, so with that said, know that this article won’t tell you, “always use 25 psi” or some other nonsense like that.

The intent of this article is to give you the skills and knowledge to figure out the ideal tire pressure for you on whatever bike or terrain you’re riding now and into the future. The right range is actually quite small so learning your proper psi and keeping it there is a good skill to learn.

Typical mountain bike pressures range from about 22psi to 40psi. The exact numbers are determined by what tires and wheels you’re running, what terrain you’re riding, how aggressively you’re riding, and what the conditions are. There’s also a degree of personal preference and comfort. World cup races are sometimes determined by fractions of a second but the riders run different tire pressure. They won’t be too far off, but there’s no one size fits all tire pressure for everyone – even with the same bike and same course.

Get in the right tire pressure ballpark first

If you’re the type that just gives your tires a squeeze and says “good enough, let’s shred!”, this method is a good place to start. The ballpark method will get you to think about your tire pressure and you’ll be able to dial it in from there. The first stop is your gear selection.

• For tubeless tires sizing from 2.1 – 2.4, try 25 psi in the front and rear. (+ or – a few psi for your size against average)
• For tubed tires sizing from 2.1 – 2.4 try 29 psi in the front and rear. (+ or – a few psi for your size against average)
• For tubeless tires sizing from 2.8 – 3.0, try 18 psi in the front and rear. (+ or – a few psi for your size against average)
• For tubed tires sizing from 2.8 – 3.0, try 20 psi in the front and rear. (+ or – a few psi for your size against average)

These tire pressures should get you close and will work for most types of riding. If you want to get more precise with your settings and get more out of your bike, read on!

Start with a good gauge

If you picked up a bargain floor pump to keep your tire pressure up, don’t count on it to give you an accurate pressure reading. The main focus of most pumps is to get air in your tires, not to read pressure. They’re notoriously inaccurate. Most are relatively consistent, so you can dial in a pressure and as long as you always use the same pump, reproduce the same pressure. Just don’t think it’s accurate.

If you’re in the market for a new pump, here is a hand pump and a floor pump with gauges that I love.

The gauge is likely reading the pressure at the pump and not the pressure in your actual tire and may be as much as 15 psi off the actual reading.

I recommend investing in a good pressure gauge separate from your pump so you can use any pump available and check the tire pressure with your trusty gauge.

Here’s a gauge that gets good reviews:

Once you have a reliable gauge, you can find and set your optimal tire pressure accurately and reproduce it from any pump.

Dial in the optimal tire pressure

Tire pressure directly controls the feel of your bike on the ground and two elements that must be balanced are grip and stability. Within the ballpark range, each PSI higher will increase your stability and each PSI lower will increase your grip. Finding your sweet spot within that range is the trick.

Lean toward stability: Higher tire pressure will give you a more stable feel underfoot because the sidewall of your tires will hold up better under aggressive cornering and rough terrain. High tire pressure will also cause you to lose grip as the hard tire skids against the loose or hard terrain or bounces over rough obstacles. More pressure also reduces the size of the contact patch of the tire with the ground.

Lean toward grip: Lower tire pressure will improve your grip at the sacrifice of stability and fast rolling over smooth terrain. As pressure goes down, your contact patch size will increase and the tire will become softer causing it to wrap around and over the terrain rather than pinball off of it. This comes at the risk of bashing a rim against a rock or something. If you go too low your tire will start to slide out as you corner and wallow at speed.

How to find your perfect tire pressure

Ride, rinse, repeat! Grab your pump and gauge and head out to a local trail. A short loop with varying terrain and fast corners is ideal. Don’t get too crazy, but find a good trail that will allow you to put your tires through their paces. Inflate your tires to a pressure on the high end of the range to start with. Try starting at 40 psi.

If you ride too low a pressure, you can get a pinch flat. If you want to learn how to fix a flat like a pro, read this post.

Take a lap on high PSI

Focus on how the bike feels as it connects with the ground both in the slow and flat sections as well as the corners and over bumps.

• How much grip you have in turns?
• Do small bumps and chatter make the ride feel harsh?
• How smoothly does the bike roll?
• Are you close to banging the rim?
• Do you feel fast, stable, and confident?

It can be helpful to bring along a pen and notepad to jot down the PSI as well as the feel or rating for each of the questions above. Once you feel good about your answers for the 40 psi, drop it down by 3 or so psi. Repeat the process all the way down the line until your rim starts to hit the ground when you go over bumps.

As you decrease the tire pressure, you’ll notice better grip through the corners and a more supple ride over chatter and bumps. You’ll also notice that the bike will become a bit more wallowy and not as responsive. The inflection point where grip is maxed but stability is still good is your sweet spot. Make a note of it and enjoy the ride. But wait, you’re not done yet.

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Isolate front and rear tire pressures

So far you’ve only dialed in your ideal tire pressure for both tires at once. Maximum performance and enjoyment will come after you’ve figured out your ideal tire pressure in both front and rear tires individually. Typically the front tire will do better with a bit lower psi than the rear tire.

To figure out the optimal pressure. Leave the rear pressure at the psi you identified in the first step and drop the psi in your front tire by 1 each lap around the trail until you start to hit your front rim on the ground. Take notes on each lap for each pressure and pick the one that feels the best for both grip and stability.

You can do the same for the rear tire at this point by increasing the psi by 1 psi each lap until you start to lose grip. You likely won’t be able to go any lower in the rear since you already started to hit your rim at lower psi in the first steps.

The ideal tire pressure takes a bit of work to find, but once you find it, you’ll have increased grip but also stability. Once you find it – write it down. This pressure will be your home setting that you’ll want to come back to over and over … until you buy a different set of tires or rims. Then you’ll have to repeat the process.

Adjusting for terrain and other variables

Once you get your home pressure set, you are now free to vary up or down depending on the circumstances. Are you carrying a big pack? Bump up the pressure a few psi. Are you riding loose and sandy terrain? Drop it down. How about snow? Drop it down a bit more, but be careful to not bottom out and snakebite your tube if you’re not running tubeless.

Check tire pressure regularly

So you took your time and got the perfect pressure set. You may think you’re done, but you’re not. Tires leak air over time, especially tubeless setups. To keep your ideal pressure set, you’ll have to check it before every ride. Just get in the habit of getting out the gauge each time you load up the bike. If you fail to regularly check you tire pressure, you’re likely rolling at a pressure lower than you think and run the risk of smashing a rim, burping a tire, or flatting a tube.

Another quick tip is to always check your tire pressure soon after inflating with a CO2 canister. CO2 permeates right through butyl rubber bike tubes so if you fix a flat with CO2, you could be losing pressure much quicker than with normal compressed air.

Conclusion

If you want to improve your bike performance by a significant factor without dropping a dime, dial in your tire pressure. It will give you more confidence in corners and more stability at speed. Use a methodical approach to get it right and do more than the quick squeeze check we’re so apt to do.

To learn more about mountain biking skills, tips, and tricks, be sure to visit our mountain biking page.

If you have additional experience that’s helped you get your pressure dialed, share the love in the comments.