Tubeless tires have revolutionized mountain biking. You can run lower pressures, small punctures don’t end your day, and pinch flats are a thing of the past.

But, eventually, you will put a hole in your tubeless bike tire. It might be a small puncture that your sealant can’t quite take care of. Or it could be a big tear in the sidewall. Either way, you have to fix it.

Here’s what to do when things go wrong with your tubeless setup on the trail. We’ll start with the easy stuff.

1. What to Do When Your Tubeless Bike Tire Burps Air

If you land hard, rail a corner at high speed, or hit a rock in the wrong way, your tubeless tire can “burp” air. All this means is you knocked the tire bead off the wheel and lost some air. It’s no big deal, but it makes it much harder to ride.

When you do this, there’s only one fix: put some air back in the tire. Use your pump or CO2 inflator to get it back up to pressure. (We’ll talk about a pump vs. CO2 in a bit.)

The best way to deal with tire burps, though, is to prevent them in the first place. There are lots of theories on how to prevent tire burping, but most of them come down to two things: run enough pressure and don’t use a big tire on a small rim.

Syntace’s graphic shows exactly why a narrower rim can cause high-volume tires to burp.

“Enough” pressure, of course, depends on your weight, riding style, and terrain. There’s not much you can do here except experiment. But if you find something that seems to work well, be wary of going any lower. If you go through a corner at high speed, you’ll put a lot of lateral pressure on the tire, and that can unseat the bead.

As for tire choice, look at your wheel width. If you have a 30–35mm wheel (or even wider), you can run a big tire without risking the bead coming off. If you’re on a 25mm wheel, run a smaller tire (maybe in the 2.25″ range) or more pressure.

Pay close attention to how often you burp your tires. If it’s happening a lot, change your tire setup.

2. Sealing a Puncture With a Tubeless Tire Plug

Tubeless sealant is great when you have little punctures—thorns, small pieces of glass, and small rocks generally don’t pose a problem.

But what if you get a bigger puncture than that? Your sealant might not be able to deal with a roofing nail, for example.

In cases like this, a tubeless tire plug can be a lifesaver.

There are many kinds of tubeless tire plugs, but they all work on the same principle: you use some sort of tool to insert a small piece of sticky rubber into the puncture.

Genuine Innovations’ tubeless tire plug is a popular option.

After you remove the tool, the plug keeps any air from escaping. And you don’t even need to take your tire off of the rim. Here’s the process:

Find the puncture. Remove the offending object. Insert the tire plug, following your particular plug’s instructions. Reinflate the tire using a pump or CO2 cartridge.

In most cases, this will solve the problem. Larger punctures might require multiple plugs.

When you get home, you can remove the plugs and apply a proper patch. Or you can leave them in. Some people have left them in for months or years without any leakage.

3. Installing a Tube for Larger Punctures

If you don’t have plugs, or you have a puncture that’s too big for them, you can install a tube. The process is the same as putting a tube in any other tire, with a couple of exceptions.

Here’s how you do it:

Remove one side of the tire from the wheel. (You might need a burly tire lever to get the bead off the wheel. Metal and heavy-duty plastic options work well.) Pour as much sealant out of the tire as you can. Remove the valve stem (unscrew the nut around the stem and push it out through the inside of the rim). Don’t forget to zip it into your pocket or bag. Insert the tube as normal. Reseat the tire bead. Reinflate the tire using a pump or CO2 cartridge.

At the end of this process, there’s a good chance that both you and your bike will be covered in tubeless sealant. That’s just how it is, so don’t worry about it.

4. Using a Tire Boot for Sidewall Tears

A sidewall tear is about as bad as it gets. Big gashes in your tires are hard to deal with. When your sealant fixes a small hole or you put a tube in, you can ride pretty normally back to the trailhead. But if you gash your sidewall, making it back without having to walk is the best you can hope for.

The best way to repair a sidewall tear on the trail is with a tire boot. A boot is just a piece of material that covers the tear on the inside of the tire and keeps air from leaking out.

You have two options for tire boots. You can use a purpose-made tire boot or rig one up yourself. A professionally made tire boot usually has adhesive on one side so you can stick it to the inside of the tire and seal up the tear (be sure to clean the site as much as possible to get better adhesion).

Park Tool’s emergency tire boots are a good bet . . . but so is duct tape.

If you want to rig one up yourself, you can use just about anything: duct tape, a piece of an old tube, an energy gel packet, even a $20 bill.

No matter what you use, you’ll take the same steps as you would for inserting a tube, with some small changes:

Remove one side of the tire. Pour as much sealant out of the tire as you can. Remove the valve stem. Clean the site of the sidewall tear. Insert the tire boot so it covers the tear (apply the adhesive if you’re using a ready-made boot, or try to stick your boot where it won’t slip if you’re not). Insert a tube. Reseat the tire bead. Reinflate the tire with a pump or CO2 cartridge.

Be extra careful when you’re riding home on a booted tire, especially if you used something without adhesive.

Air vs. CO2 for Tubeless Tires

In all of the repair instructions above, you finish by reinflating the tire with either a pump or CO2. But which should you use?

All of the normal considerations apply. CO2 is faster and a hell of a lot easier, but you’re also limited by the number of cartridges you carry. A hand pump takes a lot of effort, but you can use it as many times as you want, you can’t mess it up, and you can lend it out to people you meet on the trail without losing any flat-fixing capabilities.

But there’s another factor to consider with tubeless tires: CO2 doesn’t react well with latex-based tubeless sealant. It causes the sealant to coagulate, making it much less effective. So you could be more likely to get flats through the rest of your ride.

That said, some people still use CO2 and just swap out the sealant when they get home. They don’t find it to be a big deal at all.

Now that you know the pros and cons of each, you can decide for yourself.

Be Prepared for Trailside Tubeless Tire Repairs

Tubeless tires are great for riders who hate fixing flats (which is, as far as I can tell, everybody). But at some point, you’ll do more damage than your sealant can fix.

The best advice I can give you is to be ready to repair your tires. Bring the right equipment with you (namely a plug or two, a tube, a boot, and a hand pump or CO2 inflator). The better prepared you are, the easier the process will be.