14 Sep 2013

Mounting tight tires


Sometimes it can be difficult to mount a specific tire on a specific rim. It should be simple but feels impossible so you’re not happy at all. But don’t give up hope — think of it as a puzzle.


Rims and tires are built to different tolerances but within a range that lets them work together. Tolerances are not all the same. Tubeless setups are built to tighter tolerances, which is evident when mounting. If you’re having problems with a particular rim, what kind of rim tape are you using? A thick cloth tape (e.g. the venerable Velox) can be the cause. Try Veloplugs or a thin tape like Stan’s. If you’re using tubeless-compatible rims, do not use Veloplugs. Stick with Stan’s. The idea is to make more room in the rim channel to manipulate tires where little differences matter.

Tools and techniques

  1. While working a given bead, ensure the mounted part sits centrally in the inner channel. There is more room in the center because the channel is deepest there. The bead can migrate as you work so keep this in mind and reset as needed. Pulling the tire in the direction of the unmounted part can be helpful when resetting the bead. This creates slack needed to finish the job.
  2. Work the second bead starting opposite the valve.
  3. If working the bead in one place causes it to unmount in another, hold the mounted part in place with a strap acting as a third hand. A toe strap works very well. In the field you might re-purpose the attachment strap from your saddlebag if you don’t ride with toe straps.
  4. It’s natural to work by pushing under the bead but the bead can be pulled too. Pull the bead by rolling the whole tire over the rim with your fingers and palms. Push and pull.
  5. Lube the tire beads and rim edges with a diluted dishsoap solution. This can make it easier to push the bead over the rim. Bike-specific tire lubes exist but the soap from your kitchen is fine.
  6. Lube your tubes. Some expensive tubes come pre-coated with talc but you can shake tubes in a bag of powder as well (like coating chicken). Dusting the inside of the tire is good too and less messy. Talc acts like tiny bearings that make the tube move smoothly relative to the tire.
  7. Use a tool like the inexpensive Kool Stop bead jack. This tool is better than a tire lever because it’s more rim friendly and works a lot faster. The bead jack works by pulling the bead against the far edge of the rim so less force is required compared to a tire lever on the near side.

Of course some of these strategies are only appropriate in your home shop. The good news is tight tires can stretch after the first few rides so fixing a flat on the road gets easier.

Another perspective

A tight tire may be a blessing in disguise. What happens in the event of a blowout and sudden total deflation? A loose tire may roll off the rim leading to a crash. Tight tires tend to stay put.