There are times when inflating a tire that you might overdo the pressure. For example, if you’re using a high powered air compressor. Or, maybe you just need a little more grip on the trail, so you need to lower the tire pressure. Either way, knowing the right way to deflate a bike tire is best.
The method you use to let the air out of a bike tire will depend on the type of valve installed. Some valves are easy like Presta’s, but others are prone to damage if you’re not careful.
In this article, I will explain the three most common valve types of bike tires and the best method for lowering the pressure in each corresponding tire. Please stick with me. I’ve got a few tricks in mind that will help you, I’m sure. Let’s start with understanding the different valve types and why knowing how the valve works are essential.
Understanding Bike Tire Valves: Schrader, Presta, and Dunlop (Woods)
I’ve talked about tire valves before, so I won’t go too deep aside to mention that you can read my guide: Presta vs. Schrader Valve (Is One Better). However, to help those of you who don’t want to dive too deep into valve types, here’s a brief rundown of each type:
If you want to know what a Schrader valve looks like, just look at any car tire (or bike under $1000). Most cheap to mid-quality bikes use Schrader valves. They are rugged, durable, easy to use, and the type you will find on car tires.
Gas station air filling stations fit Schrader valves exclusively. The downside is that they are slightly bulkier and heavier than Presta valves, so you don’t find Schrader on most high-end bikes where weight is a serious consideration in the wheels engineering.
Walk into a high-end bike shop, and you’ll find where Presta valves have made a name for themselves. You’re probably wondering why Presta valves are used if Schrader is the car industry standard, and thus much easier to find pumps to fit. Well, there are two reasons why Presta valves are on high-end bikes.
- Seal Quality.
Presta valves are lighter than Schrader valves. Furthermore, Presta valves have a superior seal, so slow leaks from the valve are uncommon. On the other hand, Schrader is known to occasionally leak in the valve. The valves are easy to replace, so the vehicle industry never bothered to evolve. At the end of the day, Presta valves are better made, quality, lighter, and provide a better seal. Now, do you see why they are found on high-end bikes?
Dunlop (Woods) Valves
Dunlop, also known as Woods valves, are rare but not altogether gone. In fact, they are pretty common in Europe and Asia. In contrast, in North America, we are buried in Schrader and Presta valves instead.
Woods (Dunlop) valves are similar to Presta and Schrader – they are thin like the Presta but have an internal core release like a Schrader. But, although they have a similar actuation to the Schrader, standard Schrader valve fit pumps won’t work on a Dunlop. You need the same sort of adapter as is used for Presta valves.
Now you should have a pretty good understanding of each valve type, so go ahead and jump to the next section. Pick the instructions that match your valve type, and I’ll share my best methods for deflating and inflating via the valve type.
Method 1: Deflating a Schrader Valve Bike Tire
I use a simple rule regarding tire inflation and deflation: Always have a gauge in hand. You can pick up a digital gauge if you want, but I like the old-school kind with the clock-like face.
Years ago I bought the Topeak D2 digital pressure gauge and I love it. It has a button on the side to precisely release air while watching the pressure reading. Read more with this shortcut link to Amazon 👉 Topeak D2 Smartgauge
Here are my steps to deflate a Schrader valve inner tube/tire:
- Determine the appropriate pressure you want the tire/tube to have due to your deflating the tire. If you are taking all the air out, disregard this step and proceed.
- Remove the plastic dust cap and set it aside.
- Check the pressure to see where the starting pressure is.
- Using a blunt tool or the valve cap to apply pressure directly to the valve pin located in the valve stem. Be patient slowly releasing air is much better than releasing massive amounts.
- Carefully watching the pressure gauge, slowly release the pressure of the gauge against the Schrader valve end, so you hear hissing. Follow the following general instructions for determining the air pressure removal process:
- If a minor pressure loss is a goal, release air using the gauge in 1-2 second bursts, and re-check the tire pressure. Repeat this process until you reach the desired pressure.
- If a major amount of pressure loss is the goal, release air using the gauge for 2-5 second bursts. Re-check pressure after each burst. Repeat this process until you reach the desired pressure.
- Replace the dust cap.
If you’d like to learn about the differences between Schrader and Presta valves, check out my article here: Presta vs. Schrader Valve (One Is Better).
Method 2: Deflating a Presta Valve Bike Tire
Using a gauge similar to deflating a Schrader, here is how I deflate a Presta valve tube/tire.
- Decide on the final pressure you want the tire to have.
- Remove the dust cap from the valve on the tire.
- Unscrew the valve locking nut, ensuring it is all the way up the valve post. You should be able to tap it and let a touch of air out.
- Install a Presta valve adapter. The adapter screws over the Presta valve body. The adapter will let you use any normal Schrader air pump or pressure gauge.
- Using your pressure gauge, check the pressure. You’ll notice that the gauge can depress the valve and let the air out.
- Depressing the gauge but allowing air to escape is how I deflate my tires when I only want a bit of air to come out. If I’m changing tires or something to remove all the air, I will merely depress the nut on the valve as per step 3. I don’t bother with the adapter if merely deflating the tire pressure completely. If you want to only drop a bit of pressure, installing an adapter and using a gauge is the best way. If you have a gauge that fits without an adapter, even better.
- Once you have the tire at the desired pressure, remove the adapter and replace the dust cover.
I seriously recommend the Topeak Digital Smartgauge. It has accurate reading and plus a “air release button” to tune your tire pressure.
If you’d like to learn more about Presta Valves, read my article here: How Do Presta Valves Work?
Method 3: Deflating a Dunlop Valve Bike Tire
Dunlop valves are quite popular in Europe and parts of Asia. As mentioned above, they are sort of a hybrid between Presta and Schrader.
That is, they work in the same way that a Schrader valve works, but they are not as wide as a Schrader valve, so in this sense, they are more like Presta. Here’s my method to inflate/deflate Dunlop valve tires/tubes as needed:
- Decide on the end result pressure you want.
- Remove the dust cover from the valve and set it aside.
- Install a valve adapter. Sometimes a Presta valve adapter will work, but check the threads first – you don’t want to cross-thread the valve.
- Once you have the adapter on the valve, it’s basically the same as a Schrader valve. You will want to have a gauge in hand and check the pressure.
- Using short bursts, release the gauge from the valve so you let some air out. Then press the gauge firmly back onto the valve to check how much pressure you’ve released. Repeat this process until the desired pressure is achieved.
- Remove the adapter and replace the dust cap.
Additional Tips for Deflating Bike Tires
Releasing tire pressure is pretty straightforward. If you can pump a tire up, you can release air. Simple, right? You’d be surprised how many people make mistakes here, so I will point out a few things you may or may not have considered.
Watch out for Pinch Flats
I’m not too fond of pinch flats. A pinch flat occurs when something jars a tire, and the inner tube can ‘bubble out’ at the rim. When the deformation ends, the tire pinches the tube as it wants to return to position. The inner tube often ‘pops’ at this point, causing what we dread – the pinch flat.
If you have to remove air from your tube/tire, ensure that you don’t let air out, and put pressure back in if a part of the inner tube is folded or pinched between the tire and rim.
Watch For Dirt in the Valve
One of the worst experiences I’ve ever had with my bike happened at a gas station where I added air to a tire. I was about to embark on a day of riding when I stopped to check my tire pressure at a gas station. I installed my Presta to Schrader valve adapter and popped the air pump on to top up the air.
The air gauge on the pump wasn’t working, so I grabbed my gauge and checked the pressure. Well, as luck would have it, a grain of sand from the dirty end of the air pump at the gas station had somehow gotten inside the valve adapter. When I checked the pressure, the air release for the split second as I installed the gauge was enough to send that tiny grain of sand flying.
It flew right into my eye. I had to go to a clinic and have my eye flushed.
It may sound paranoid, but I strongly recommend using safety glasses when working with compressed air. Your eyes will thank you.
Learning about Mountain Bike Tires could take years. Let me help you just a bit quicker with some articles.
- Can a tire be great for both street and trail? – Find out in this article: Best MTB Tire for Street and Trail
- Are 26 inch Tires Dead? Heck no…Read – Who is a 26 inch MTB For
- Love playing in MUD – Read What tire is recommended – Mountain Bike Tires for Muddy Conditions
- Rocks can destroy a mountain bike tire – Find the Best MTB Tire for Rocky Conditions (PRO RECOMMENDED)
- Thinking about getting a 26 inch MTB let me help – Should I Get a 26 Inch Mountain Bike?
- Does sand slow you down? It might be you’ve got the wrong tires. Read – The Best MTB Tires for the Sand
Common Questions About Deflating Bike Tires
Can I use my fingers to deflate a bike tire?
You can use your finger to deflate Presta valves easily enough. However, Schrader valves are a bit trickier, and Dunlop valves are nearly impossible to deflate with your finger. Your best bet is to use a pressure gauge, as I’ve described above.
How much air should I let out for different terrains?
The standard for mountain biking is to maintain a PSI of 30-50. That is 30 pounds per square inch to 50 pounds per square inch. Here’s my rule for inflation per terrain:
For Rugged, Bumpy, Sand, or Slick Conditions: Less is more. Use around 30-35 PSI if you need softer, stickier traction.
For Hard-Packed Trail, Hard Gravel, or Road: More is better. Run your tire pressure closer to 50 PSI for a smooth ride on hard-conditioned ground types.
It seems like I’m either: buying, replacing or airing up bike tubes
🚴♀️ Can I put a tube in a tubeless tire? I explain with video 👉 Can I Put a Tube in a Tubeless Bike Tire?
🚴♀️ Presta vs Schrader which tube is better. Find out 👉 Presta vs Schrader Valves (Is One Better)
🚴♀️ I kept getting flats, are some inner tube brands better? Check out what I think 👉 Does the Brand of Inner Tube Matter?
🚴♀️ Are you getting a bunch of flats? Read 👉 Don’t Get Caught with a Flat: Why Rim Tape is a MUST
🚴♀️ Is there a right way? 👉 How to Let Air Out of a Bike Tire
🚴♀️ Presta Valves it’s a mystery 👉 How to Inflate an MTB Tire with a Presta Valve
Re-Inflating Your Bike Tires: What You Need to Know
CAUTION: Always check the tire sidewall for inflation maximum. You don’t want to blow a tire/tube while inflating.
Re-inflating is common when you’re mucking around with tire pressure – especially when you let too much air out of the tire. Luckily, re-inflating is simple. Just follow the instructions for deflation, but instead, add a pump and add pressure instead of releasing it. Remember to wear your safety glasses and confirm the pressure before you start and regularly during inflation.
David Humphries is the creator of DIY Mountain Bike. For me a relaxing day involves riding my mountain bike to decompress after a long day. When not on my bike I can be found wrenching on it or making YouTube videos at 👉 DIY Mountain Bike Read more about David HERE.