Tire falls off the rim...

Is there a rim lock on that wheel?

Chili said:

Figure your odds are better of getting an answer by starting 3 identical threads?

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2 are now gone.

I'm not sure I know what you mean here. The tire was coming off the rim, but the bead was still in place?

Did the tire go flat? Because once that happens the bead will move towards the middle of the rim and then the tire can walk all over and work it's way off.

Or did the bead simply start pushing over the edge of the rim? Really stupid question -Did he put a 19" rear tire on an 18" rim (and not notice while doing it)?

Post some pics if you can, then a few of us could try and help.

Sounds like he's running it with super low air pressure. Or he used a 20 inch bicycle tube in there. :)

But seriously, there isn't enough force holding the bead outward against the rim. It's got to be air pressure.

I am a little confused.

In the first post, acesnkush said "The bead is in place". "is", present tense, indicating that after whatever happened the bead was still in place.

In a later post he said "the bead was in place", possibly indicating that now it no longer is.

If the problem is that the bead has been knocked off its seat on the rim then he needs to either run higher air pressure or stop running into curbs/rocks.

If the bead is still in place then it sounds like the tread is separating from the tire. In this case he needs to buy better tires.

I understand that you are fairly new to the sport, and may not have all of the terminology, unfortunatley it makes it harder to visualize what the problem is. The bead is the part of the tire that is supposed to be in contact with the rim. It is the part, on each side of the tire, that has the smallest diameter. It appears that you are using the term bead only to refer to the part that it actually clamped down. When you say "lip" are you referring to the lip of the rim? The tire coming off of the lip of the rim, the bead, which goes all the way around the rim, is clearly not in place, but it may still be locked down with the rim lock.
It sounds like your friend had the wrong size tire on the wheel. The wheel diameter should be stamped on the outside of the lip, along with the wheel width (1.85X19 for example), and the tire size is on the sidewall (110/90-19). My examples were for a 19 inch wheel and tire. But if the problem continues with a different tire, there could be a problem with the rim.

I've had this happen before, the problem was as Papakeith said, the bead was damaged. It wasn't immediately looking at the tyre but the wire in the bead had snapped. I'd say replacing the tyre will sort the problem out. The rimlock shouldn't be an issue, its main job is to stop the tyre rotating on the rim, not hold the tyre onto the rim. So assuming you're putting the right size tyre on there I reckon a new one will sort it.

acesnkush said:

The bead was and is in place. It never left.

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If the bead was and still is in place then there isn't a problem! Like others have said, we have a terminology problem here......

acesnkush said:

We checked the air pressure like 5 times and it was right.

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And what was that air pressure?

acesnkush said:

It takes like 5 min of riding for the tire to come off the lip. And its always in this one spot (like 7 or 8 inches up from the bead thing)

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If the tire comes off the rim, it must be coming off at the bead. The tire sidewall can't be more than 4 or 5 inches tall so I don't know where you are measuring 7 or 8 inches. When you say "bead" are you referring to the valve stem (where you put air in) ??? Does it start peeling off the rim 7 inches radially measured from the valve stem? Is there a bend in the flange of the rim at that spot?

acesnkush said:

Ill try to get a pic... But all it would show is where the tire starts to come off the rim...

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If you can show us a picture with the tire in the bad condition then we will at least get the terminology figured out.


A bit of glossery:

Bead: the inner most diameter of the tire. The bead is heavily reinforced with steel wires so that it doesn't stretch and holds tight against the seat.

flange: The largest diameter of the rim. To install the tire the tire must be pryed over the flange. The flange keeps the tire from slipping off the seat to the outside. (air pressure and a slight "bump" keep the bead from slipping off on the inside). Note that the flange can be easily damaged from hitting rocks, curbs, etc.

seat: The part of the rim that is in contact with the tire bead. When measuring the size of the wheel it is the diameter of the seat that matters, not the flange.

Rim: what the tire mounts to. Generaly used to describe the collective parts of the flange, seat, etc.

valve stem: Where you put air in. Part of the tube on a tube type installation, or mounted in the rim on a tubeless installatation.

Wheel: the assembly of the hub, spokes, rim etc.



I suspect that the problem is that the flange is bent and/or broken. Hitting a sharp corner hard, such as a curb, can bend the flange even when the air pressure is proper. Riding on low air pressure is asking for a bent flange. Riding on a flat tire will almost assure a bent flange.

Send a picture if you can, then we can stop guessing.

If you do end up looking for a rim I'd talk to these guys first!

LINK