Tubeless tires use a thicker tread area and sidewall to prevent punctures. This allows riders to run lower pressures for more grip. The lack of tube also creates lower rolling resistance. Tubeless rims are also specially designed to form an airtight seal with the tire.
The tires typically have a soft compound rubber on the inside of the tire to “grip” thorns that do penetrate, thus not allowing air to pass out.
Avoiding punctures with Tubeless tires
Regardless of the thicker construction and soft compound lining, these tires do sometimes get a puncture which causes them to lose air.
The best way to avoid this situation is to use a tire sealant such as Stan’s NoTubes. A small amount of this sealant will prevent even large holes from becoming an issue. You may need to re-inflate the tire after a major puncture, but no other repair is required.
Tubeless tires also sometimes “roll” off the rim because of the lower pressures used, causing them to burp air. This can lead to dirt getting between the sidewall and the rim, preventing a good seal. Sealant will sometimes turn this goop to glue, but not always.
If you are not using sealant, you have got dirt in the bead/rim interface, or the tire has a major gash in it, you may have to “tube” the tubeless tire.
Putting a tube in tubeless tires
The procedure for tubing tubeless tires is the same as for regular tires. However, before you can put a tube in you must remove the valve stem by unscrewing the retaining nut from the outside of the stem and then pushing the whole valve unit into the rim from the outside. This will unseat the valve seal from the rim and allow you to pull the valve out. Keep the valve safe, as you will want to replace it later.
With the tubeless valve removed, you can place a tube in the rim in much the same way as a regular tire. You will most likely have more difficulty getting the tire bead back over the rim. Make sure that the tire’s bead is sitting in the lowermost indentation in the middle of the rim, and work the bead round, pushing it away from you with both hands until you get to the far side of the rim. At this point, it should be possible to roll the last portion of tire bead over the rim. If you really must use plastic tire levers, do so very carefully so that you do not pinch the tube between the lever and the rim.
Re-inflation of tubeless tires
Tubeless tire beads tend to “snap” on to their rim. Ideally, you should inflate the tube to 50 PSI and listen for the tire making cracking noises as it seats in the rim. If you can’t reach 50 PSI because of a poor pump, be prepared for cracking noises that sound almost like a spoke breaking as you ride along.
Tip: If you find yourself on the trail with a pump that seems to be sucking more than it blows, try taking it apart and dropping oil on the plunger washer. This creates a better seal.