Originally Posted by
icemilkcoffee
Yup. As I said in that previous thread, the XR26T has no lip at all:
And unlike what Kinlin's drawing shows, there is no discernable slope neither. I was already worried about that when I first started using this setup. But now my fears have come true. The rim loses the bead in a blowout.
It looks like the part of the bead seat of those rims closest to the middle are a larger radius from the wheel center than the part close to the vertical sides. So in effect it is doing the same thing as those bumps do in the cross section drawing you posted. If you cut a strip of paper with a straight edge on it between rims sides and spanning the two bead seats, I think you'll see it. Or at least be able to tell me I'm wrong.
To me looking at your picture, it does somewhat look like the xr-31 cross section that
Spoonrobot posted.
Even if tape does get put over those two bumps on a rim that has them, it's still making the diameter of the bead seat at that point larger. And I'd think that in most cases, that will help keep the tire bead on the bead seat since the part of the bead seat next to the wall will be less diameter.
Otherwise I don't have a clue why you had the issue. Perhaps it is the tire. Especially if it was too easy to get the tire on and off.