Not sure what is going on here – (new) Schwalbe NN on a Crest Rim – pumped it up to about 40 psi and it blew off the rim. (Face full off tubless fluid 🙁 )
Tyre bead now distorted and would not seal, so put a tube in it, got to 30psi and the same happened, tube split. Coincidence or is the tyre knackered/stretched now for such a shallow rim? Had done about 50 off-road miles without problems, but not feeling that confident now 😐
Anyone experienced similar? What do you reckon?

Deformed/poorly finished rim/tyre bead/hook at some point?

Sounds like a dodgy tyre rather than a rim issue.

(new) Schwalbe NN on a Crest Rim

Had done about 50 off-road miles without problems

So is tyre new or is it used? or do you mean the rim?

Chances are tyre was either oversized or didnt seat right in first place, wither way its now bin fodder. You could try sending it back, but unlikely youll get anything for it as they are not officially rated for tubeless use (unless you bought UST one?)

Tyre ****, happened to me a couple of months ago but it was an old one. Full face money shot. 😆

Never had a spaff shot explosion yet but just in case, I always pump up the wheel with it round a corner… 😀

Thanks – just to be clear the tyre had run ok on the rim for 50 miles or so. Both rim and tyre were new before that, latest type ‘Tubeless Ready’ NN – thats why I was pumping it up, again…

Sounds from your description like the tyre bead has broken…

Strange way for it to happen though. Did you have a big fight to get it fitted when originally mounted?

Send the tyre back, I’ve ridden down steps and off drops with tyres at 60psi on stans 355, no problems.

I had this happen on a kevlar beaded Maxxis and Crest rim. but I got it to 65 psi before it went.

It seats and seals fine at 40psi but looks a bit uneven. Is the tyre knackered or just badly seated? Doesn’t look knackered but how can I tell?

did you use a compressor to originally fit the tyre or pump it to over 40 PSI by any chance?

That’s usually the culprit as stans systems do put more strain on tyre beads and are only designed to work with low pressures. If you over do it the bead on the tyre can stretch and let go with a full on bukake moment.