acesnkush

Member
Apr 29, 2006
86
0
So my freind has a beast of a bike. He has a 1980 yz 465. We were riding this weekened when his tire started coming off the rim. It started at one point and slowly went more and more. We have no idea how this can happen. The bead IS in place and doesnt look damaged. The tire is a new tire. He has only ridden on it 3 or 4 times. We spun the rim with the tire on and off and it looked startoght with no kinks. He is reluctant to buy a new tire again because he is a cheap guy. Any suggestions? Its a freaking mystery. If by chance he needs a new rim... Anyone know where to look for vintage rims..or would a new one fit?.
 

adam728

Member
Aug 16, 2004
1,011
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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)?
 

acesnkush

Member
Apr 29, 2006
86
0
Hmm... It has a rim lock

And yeah the bead was in place, and no it wasnt flat. The tire size Im not sure about...but like I said he rode on it before and it never happened. And the bead wasnt pushing over the rim.... The tire just slowly strats to come off the rim on one side
 

YZ165

YZabian
May 4, 2004
2,431
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Post some pics if you can, then a few of us could try and help.
 

adam728

Member
Aug 16, 2004
1,011
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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.
 

rmc_olderthandirt

~SPONSOR~
Apr 18, 2006
1,533
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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.
 

acesnkush

Member
Apr 29, 2006
86
0
The bead was and is in place. It never left. Yamaha changed the tire and the tube so I am pretty sure they didnt use a bycicle tube. Lol I know how wierd this sounds... its so wierd none of us can figure it out. The tire he got was a brand new dunlop tire. We checked the air pressure like 5 times and it was right. 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) and its starts slowly coming off. I know this sounds vague but I HAVE NO CLUE what can cause this. its a freaking mystery we cant figure it out. Ill try to get a pic... But all it would show is where the tire starts to come off the rim... If it helps I THINK its on the chain side.... I think


Thanks guys for th help!!! I must say this is like the best site because of all the cool guys out there willing to help a brother out. Thanks guys
 

Papakeith

COTT Champ Emeritus
Damn Yankees
Aug 31, 2000
6,695
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My guess is that either it's the wrong size tire, or you damaged the bead while installing it.
 

FruDaddy

Member
Aug 21, 2005
2,854
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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.
 

Zenith

Member
Jan 11, 2001
483
0
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.
 

rmc_olderthandirt

~SPONSOR~
Apr 18, 2006
1,533
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acesnkush said:
The bead was and is in place. It never left.

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.

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)

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...

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.
 

acesnkush

Member
Apr 29, 2006
86
0
Ok.. yes I think I got some of the terminology wrong. The tire that was coming off was 7 or 8 inches from the RIMLOCK. not the bead. And we took the tie off and the BEAD ( the thing in the tire) was still there. The tire size was right, I checked it myself. Lol I know.... Man I wish I can just virtually show you guys it. I dont know... His bikes a monster but vintage as hell. So out of the vagueness I said in the earlier post... Maybye I didnt say this before but where it is peeling off the "flange". I think he should get a new tire and see where it goes from their. I guess my main concern would be if he needs a new rim. Because where the hell can you get a Yamaha 1980 yz465 back rim?
 

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