Tyre Popping Off Rim

[awol]

So I build a wheel with a cheap chinese rim and fit a new marathon plus tyre with new inner tube. Pumping it up to 50psi I get a tyre bulge near the valve.
Q1 What causes this bulge ?
So I re-fit it all and only pump up to about 40psi which is just when the bulge starts, but now I got the tyre popping off the rim at that area.
Q2 What causes the tyre to pop off the rim?
The tyre appears to be fitted as good as I can,sitting equal all round, so I decide the cheap rim must be made too small and order a decent Mavic rim.
But comparing sizes they are the same so I'm out of ideas.
Is it just my new tyre or inner tube (which have been in my garage for a few years) are kna**k*rd?

 

[Deleted member 4366]

I had one pop of while riding it. I put it back on, but it popped off again within 100 meters. It was also a Marathon Plus.

The first time I fitted it, it didn't look right at all. It was very difficult to get the bead concentric with the rim. I guess that the tyre had been abused by folding or previously levered off without pushing the bead into the well. I had to replace it even though it was a nearly new tube.

There was no problem with the replacement tyre. AFAICT, the tyre had previously been fitted to a motor wheel, then taken off and re-fitted to a normal wheel before it was given to me to convert.

Not all rims are the same, so it might be OK on a bigger one.

 

[LeighPing]

Maybe it will be ok on the other wheel?

 

[awol]

Maybe it will be ok on the other wheel?

Might be, I am going to swap it with my other wheel later to try.
I don't understand why the inner tube bulges near the valve though either.
Any thoughts?

 

[Deleted member 4366]

The bead has stretched. It's the tyre that's faulty, not the rim.

 

[Artstu]

Faulty tyre, I've had exactly the same issue on those tyres and got a replacement tyre and tube under warranty.

 

[awol]

got a replacement tyre and tube under warranty.

Ah, these have been sat in box in my garage for a couple of years.
The tyre did have a twist in it when I got it out of the box so sounds like your both right with a fault and it being in a bead, but this leads me onto could I have caused it by storing it upright shoved in the big box it came in with some other stuff?
Might start a new thread on that.

 

[Deleted member 4366]

Unlikely that it's caused by storage. As I said, incorrectly levering it on to the rim can do it. Maybe you got Artstu's tyre after he sent it back, which somebody else sent back before him.