Bead seats, but won't stay seated

Just changed the rear tire on my Seca 750 (Bridgestone S11 Spitfire). I've removed the valve core and can easily get the beads to seat with a distinct pop, but when I let air out, they pop back off. If I put the valve core back, they pop in place at about 30psi, and soapy water at the seam of rim and tire doesn't bubble. The mold line around the rim area has an even gap all the way around the tire on both sides.

Is this safe to put back on the bike and ride? If not, what do I need to do?

 

If there are no leaks and you are sure the mold line is even all the way around, you should be fine.
That line is key to making sure it is seated properly.
If the line is pulled in toward the rim anywhere, hit the tire with a rubber malt and it usually pops out.
Cheers

 

hmm. kinda sketch. not to ask the obvious question, but are you sure the tire is the right size?

if it was on a car, I'd say screw it and throw it on. being on a bike and knowing that 50% of your life is riding on that tire, i'd make sure its perfectly right before putting it back on and trusting your livlihood on it.

but thats just me...

blowing the bead off at 75 just usually doesent sound like a very happy ending, :O

 

A while back a member had trouble like that. On the rim is it stamped "tubeless" if not you may be trying to install a tubeless tire on a rim that needs an inner tube. Or you have an inner tube tire that won't work on a tubeless rim. You need to look at a service manual to see what kind of rim you have.

 

Tires are wrapped kinda tight to make it easier to mount them. If the bead seats, and doesn't leak, then don't sweat the fact that it will unseat from the rim when air is let out right after it is mounted on the rim. The tire still has the lube from just being mounted. Once the tire gets a few miles on it, it goes through heat up/cool down cycles, and will seat quite firmly on the rim. When I mount tires, I do so without the valvecore in, air them up to max pressure for the tire per manufacturer stamp, then put the valvecore in (wear safety glasses doing this of course), and adjust air to riding pressure.

 

I've double checked size, (and that both tire and wheel are tubeless). Stock size, same size as the one that I had put on last year and stayed put long enough to wear out.

That's me too...which is why I asked people more experienced than me.

Seems to be OK, I've got a couple hundred miles on it now.