Why Do Mountain Bike Tires Need Sealant

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Why do mountain bike tires need sealant is a question? That is what I often hear novice mountain bike riders ask.

Well, if you have been a mountain biker for quite some time, you would know its importance.

But don’t worry if you are still figuring out the different aspects of your bike and mountain biking.

I am here to help. So, lets dive in!

What Is A Sealant & Why Do MTB Tires Need A Sealant?

Mountain Bike Tire Sealant
Mountain Bike Tire Sealant

As the name suggests, a sealant liquid is used to seal gaps.

It is a special fluid that is used to seal a puncture in tubular tires and gaps in tubeless tires.

This is similar to the fluids used by dentists and woodworkers.

Proper application of sealants helps repair punctures.

For example, small holes in your bike tire can be perfectly sealed with the help of a sealant fluid.

Even though it is not a permanent solution, it can help you cover some destinations so that you can find a long-lasting solution for your flat tire.

Similarly, tubeless lady tires help in filling the gaps between the rim and the wheel.

While a pro mountain biker will be able to use the sealant without any mess, that may not be the case with a new biker.

You must remember to sufficiently vent the air before applying the sealant.

It is a good tip to follow the procedure specified by the sealant manufacturer diligently to avoid any mess.

Always carry a pair of gloves in your repair kit to ensure that your hands don’t get dirty.

4 Things To Remember When Apply Sealant To MTB Tires

Applying Mountain Bike Tire Sealants
Applying Mountain Bike Tire Sealants

Below are 4 important points you need to consider when applying a sealant to your mountain bike tires:

  1. When you apply 30-60 ml sealant per tire, remember that your bike tire’s weight will also increase by up to 100 grams. This may seem to be a trivial number, it is still significant for those riders who focus on having the least weight on their bike tires.
  2. One should not reduce the quantity of the sealant in order to reduce the weight of the tire. Remember, without a sufficient amount of sealant, it may be difficult to seal the tire puncture.
  3. Sealants are not a permanent solution to puncture or gaps. If you do not want to replace a flat tire or you are applying a sealant to fill the gaps, you will have to apply sealants periodically, preferably once every six months.
  4. Always choose a tire sealant which is of a good quality and belongs to a trusted brand.

Types of Sealants For MTB & How To Choose One

Choosing MTB Sealants
MTB Sealant Injections

If you’ve got your answer for why mountain bike tires need sealant, now let us look at how to choose a sealant for your MTB.

First, it is essential to know the popular manufacturers of tire sealants so that you don’t end up buying a low-quality one.

Brands such as Stans, Muc-Off, IRC, Panaracer, Black Ox, Vittoria, and Mavic are the most sought-after manufacturers of MTB tire sealants.

In most cases, bike tire manufacturers suggest sealants suitable for the tires they make.

Tire sealants, essentially are of two types i.e. latex-free sealants and latex-based sealants.

1. Latex-Free Sealants:

As the name indicates, latex-free sealants are free from any latex.

Latex-free sealants are made of a thicker liquid solution, which lasts relatively longer than latex-based sealants.

However, latex-free sealants are not recommended to be used for problematic tire punctures.

2. Latex-Based Sealants:

Latex-based sealants are the most common type of sealants with hardening properties of latex.

Latex thickens during the process of the dispersion of polymer bases in water-based ammonia or water.

As a result, when a hole is formed, the ammonia or water content evaporates through it, and the latex hardens, snugging onto the puncture.

One major disadvantage of using a latex-based sealant is that, with every use, airing up and down, the water evaporates more and more, gradually making the hardened latex less efficient.

Hence latex-based sealants need re-application frequently depending on one’s bike riding habits and trail conditions.

10 Common FAQs On Why Do Mountain Bike Tires Need Sealant

1. How often should I add sealant to mountain bike tires?

It is recommended that you apply sealant at least every six months to your mountain bike tire to ensure it works efficiently.

2. Can I ride tubeless without a sealant?

It is possible to ride MTB with tubeless tire without sealant.

It is because a tubeless tire has the capability to hold air even in the absence of a sealant.

However, if your mountain bike has a tubeless-ready tire, it is vital to have a sealant in order to make it airtight.

3. How long do tire sealants last on a mountain bike?

Typically, a sealant would last anywhere between 2 months to 6 months on a mountain bike tire.

Different factors determine the durability of sealants on a mountain bike tire.

Below are few durability factors for sealants when applied on a mountain bike tires:

  • Temperature and humidity.
  • Frequency of bike ride.
  • The condition in which the bike is stored (the sealant tends to last longer when stored in cold, colder conditions).
  • The thickness of the tire casing.
  • The number of punctures that the tire has.

It is recommended that a proper inspection is done at least once every three months to avoid any unprecedented flat tire when you are in the middle of a trail.

4. Do you need to remove the old sealant before applying the new one on mountain bike tires?

Even though this is considered to be more of a personal choice, I prefer removing the sealant prior to applying a new coat due to the following reasons:

  • The dried-out sealant that is on your MTB tire could water down the new mix, making it less effective and non-durable.
  • The large pieces of sealant inside the wheel can increase the weight of the tires. If you don’t want to ride on heavy-weighed tires, you must remove the chunks before applying the new sealant mix. Preferably, you should wipe the inside of the tires pretty well.

5. Is tire sealant a permanent fix for MTB tires?

Applying a tire sealant is usually not considered to be a permanent fix for MTB tires.

With time, the sealant would start losing its efficiency and will have to be removed and re-applied, more so when the puncture is large.

Therefore, once you have applied a sealant, it is advisable to check your MTB tire’s pressure prior to every ride.

6. Does tire sealant affect wheel balance?

Applying an adequate amount of sealant on your mountain bike tire is not going to affect the wheel balance.

However, if your wheel has been out of balance prior to applying the sealant, it could get slightly worse after the application.

Hence, try to correct the balance issue in your tires before applying the sealant.

7. Will tire sealants fix a slow leak?

Yes; sealants can be used to fix slow leaks in your mountain bike tires.

8. Why do MTB tires leak?

Mountain bike tires leak due to multiple reasons, few are listed below:

  • Due to the evaporation or drying of sealants.
  • When the tire rims and beads are not flush against each other.
  • When the time tape of the tubeless tire has shifted or displaced, exposing the spoke holes.
  • Because of a loose or poorly fit tubeless wall.

9. How many times can you seal an MTB tire?

While I can give you a definite answer on why mountain bike tires need sealant, this is a more subjective question.

Various factors, such as the condition of your tire, the size of the puncture, etc., would determine the number of times you can seal an MTB tire.

If your tire has started wearing off, it is better to replace it with a new one rather than reapplying the sealant.

10. How much sealant should I apply on my MTB tire?

Usually, a 2.5-inch MTB tire would require up to two ounces of sealant.

Whereas for 2.5” to 2.6” tires, you may want up to three ounces of sealant to prevent leakage.

Likewise, 2.7” to 2.8” tires need sealant up to 4 ounces.

While these are the typical amounts, depending on the area you need to cover, it would differ.


I hope this article has given you critical insight into why mountain bike tires need sealant.

P.S. Did you find this article insightful? if so, consider reviewing our detailed guide on how to check signs of low air and wear in MTB tires.

Also review our guide on why tubeless MTB tires go flat.

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Team Biking KnowHow

Rohan runs Biking KnowHow along with his team. Rohan has been a mountain biker since 2005. His mission is to simplify mountain biking for everyone. All Biking KnowHow content piece is thoroughly fact-checked. Our content is backed up with leading research and inputs from expert cyclists.