I am going tubeless! Using tubless ready rims and tires with a floor pump. The front one went on no problem. The rear one has seated, heard pinging, and holds air dry, up to 40 psi. When I add sealant it holds overnight and at high pressures, 25-35. But the moment I run my tire below 20psi the bead/rim interface leak when I push down on the tire or wiggle it from side to side. Any advice?

Using: md 40 rims Surly knards 29x3 39mm rim tape/ stans

Tried: Soaping tire bead. Wrapping tire with strap. Installing sealant (that was just a mess to clean up). Using tire levers to pre seat tire bead. Inner tube overnight. Seating tire not on ground. Letting seat overnight at 35 psi.

Here is a photo of me pressing on my tire at 15 psi using one thumb. See the soapy bubbles from air out near my thumb but a good seal everywhere else. When I put it on the ground and put some force on it it is worse. Like tons of micro burps. enter image description here


  • Can you confirm that it is indeed a new tubeless ready version of the knard and not an older version?
    – Andy P
    Mar 7, 2022 at 14:01
  • 1
    Yes. Says tubless ready right on the side. Mar 7, 2022 at 14:05
  • Try inflating to ~20psi and taking for a short (15mins) road ride for a couple of days. Sealant doesnt distribute very well and get to the beads without the rotation/sloshing around caused by riding.
    – Andy P
    Mar 7, 2022 at 15:50
  • what sealant was it? Mar 7, 2022 at 16:38
  • 1
    Andy, tried that. All it did was slowly let all the sealant and air out and flatten the tire. Added air and within 10 more minutes it’s flat. That’s after I “tended” to the tire for three days rolling it and bouncing it around my flat a few times a day. It’s not the best time spent, but it’s winter and you can’t ride that much. Using Stan’s sealant. Mar 7, 2022 at 16:40

1 Answer 1


With the information given the next thing to look critically at is the tape. (I'm assuming some effort was made with the sealant in to get it distributed all along the sidewalls, ie turning the wheel horizontal and sloshing it).

Take the tire off and examine the area for any issues like uneven coverage, poor tape width choice, etc. If you find none and it looks like it should be good, add layers (all around) to try to build up the rim a little.

  • Thanks, Nathan. I went back in and added two layers of electrical tape to one side and three to the other side. It seated with a much more affirmative pop than the last times and feels much more firmly seated. Next time I’ll try a rim tape that’s 2-3 mm wider as there were spots around the weak areas that this happened. As a precaution is it worth messing with the front one, or just let it go if it’s fine? Mar 7, 2022 at 19:18
  • 1
    @JonathanTrzepkowski What you're looking for with that question is if you were to look at the rim/tire in cross section, is the bead contacting the tape or is there some risk that there's a gap of bare rim between the edge of the tape and the start of the bead. If there is a gap, and especially if it runs all the way around the wheel, then yes I would worry that sooner or later that could be a weak spot and sealant could get up under the tape and cause problems. It's not a guarantee either way and it also depends on the quality of the tape job (how well stretched it is, surface prep, etc). Mar 7, 2022 at 20:06
  • 2
    Also TBH I would have low hopes for the electrical tape going the distance in there as a solution. The adhesive is just not all that tenacious. In almost every situation you just want to go inner rim width plus 5mm for your tape choice. If you do need to improvise something then Gorilla tape cut down with a razor to be the right width is a good way to go. (There are videos etc about how to cut it down neatly). Mar 7, 2022 at 20:08

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.