What sealant does
Tubeless sealant is a liquid that sits inside the tire. It helps fill tiny gaps at the bead, and can plug small punctures as they happen. It does not fix large cuts. Over time it dries out, so it needs refreshing.
How much sealant?
The amount depends on tire size and the brand of sealant, so follow the instructions on the bottle first. As a general idea, narrower road tires use less and wider mountain bike tires use more. Many brands give a suggested range per tire size, usually in milliliters or ounces. If you are unsure, start with the recommended amount, and add a little extra if the tire does not seal.
Can you put too much?
Yes. Excess sealant adds weight and may pool, giving a slightly uneven feel. It can also push out of the valve or bead more easily. Staying close to the recommended amount is a sensible approach.
Two ways to add sealant
- Through the valve: remove the valve core (if your valve has a removable core), then inject the sealant using a bottle with a nozzle or a syringe. This is tidy and works with the tire already seated.
- Before closing the tire: lift one bead, pour sealant into the tire, and then reseat the bead. It is simpler, but messier, and the bead must then be seated.
Step-by-step through the valve
- Deflate the tire (see how to safely deflate a bike tire).
- Rotate the wheel so the valve sits at the bottom or the top, depending on what is easiest.
- Remove the valve core with a core tool.
- Shake the sealant bottle and inject the correct amount.
- Refit the valve core and tighten it gently.
- Inflate to your usual pressure. If the bead has come loose, see seating a tubeless tire with a hand pump.
- Spin and tilt the wheel so the sealant coats the inside, and ride gently for a short time.
Getting the tire to seal
- Check that the tire and rim are compatible.
- Check rim tape and valve for leaks.
- Spray soapy water on the tire to find where bubbles form (the slow leaks guide covers other sources).
- Rotate the wheel with the leak at the bottom, so sealant can reach it.
- Add a little more sealant if the leak is persistent, and allow some time for it to seal.
How often to top up
Sealant dries out gradually. Many manufacturers suggest refreshing it every few months, and more often in hot, dry climates. Check yours by removing the valve core and looking in with a thin tool, or by pulling a section of the tire bead back. If it looks like thick rubbery clumps or very little liquid, it is time to refresh it. Your sealant brand may give its own guidance.
Do you need to remove old sealant?
You do not always need to take out all the old sealant. If it is still liquid, you can often add some fresh sealant. If it has dried into lumps or a rubbery layer, peel off what you can and wipe the inside of the tire before adding more. Dried sealant is generally easier to remove when it is fully dried.
Will tubeless tires stay inflated without sealant?
Some may hold air for a time without sealant, but it is not typical, because the bead and the tire casing can seep air. Sealant is generally considered a core part of a tubeless setup. If you are unsure, see our overview of how to inflate a bike tire properly and check your tire and rim manufacturer’s guidance.
FAQ
How do I get my tubeless tire to seal properly? Check rim tape and valve, use enough sealant, seat the bead well, and spin the wheel.
Do I need to remove old sealant before adding new? Not always. Remove dried clumps, but liquid sealant can usually stay.
How much is too much? More than the recommended amount for your tire size is not usually needed.