A few weeks ago my Fat Albert front (pretty old) was fitted tubeless and then blew off the rim. It did this a few times, so inspected the tyre and the kevlar bead was broken in the weak spot. Putting a tube in and the tyre would go wonky around this spot. I chucked the tyre.
Today I put a Hans Dampf (fairly old too) on the same rim. Seats fine. I go out, come back and find the tyre blown off the rim and a load of juice all over the garage door. Inspect the tyre, its done the same thing and the bead has broken. I cant even use an innertube, so thats another in the bin..
Looking at the rim, it looks fine? Stans ArchEX 26. I cant see any dents or issues where the rim would have trouble seating.. Anyone else had this?

What psi?!

30 or so.
I think maybe the bead was deteriorating no both tyres. I have put a newer HD on and thats staying up so far. I think both tyres were about 4 years old.

Did you run both the old tyres on another wheel? It could have had a defect that damaged the beads on both tyres in the same place, and then putting them on the slightly differently sized Stans might have caused them both to fail, again in the same place.

/sherlock

Don’t see how that would work mintimperial, unless you’re REALLY anal about your valve/logo alignments

Are the tyres tubeless ready?

4 year old tyres… There’s your problem.

4 year old Schwalbe tyres… There’s your problem.

FTFY

I had this with a Podium rim, rim looked fine, but successive tyres went bang, lost about 5! Replaced the rim in the end, and all was well.

Rim is clearly haunted/possessed.

Call in an exorcist.