Bicycle Mechanics - Tire deformation

Hello. I have a deformation of my rear tire, which makes the rotation of the rear tire uneven. By deformation (let's say vertical deformation) I mean that the tire width from the rim to the outer part of the tire (which touches the ground) is not equal at all places of the tire, also it has a horizontal deformation, which is obvious if I rotate the wheel and look at it from above; then I can see that the tire is "going" either to the left or to the right side.

The rim is perfect (no deformation).

While going at high speeds (40-60 km/h) this deformation is really obvious and it makes the bike shake to some level, and I can hear the sound of the tire hammering. I am really afraid not to lose the tire on-the-go.

Can I do something to reduce the deformation (unfortunately one cannot find good quality tires over here, so I would rather keep the old one if it's possible to correct the problem)

Thanks.

That should fall under warranty! I've noticed that with a few of my own, and had the LBS deal with them.

Are you sure that the tube is properly installed and inflated in the tire? Unless the rubber of the tire itself is of poor quality, it seems as though the problem could be a result of improper inflation/installation. Try deflating the tube, reseating the tire, and then slowly reinflating, making sure that the tube/tire is being installed correctly.

-Moab

When you look at the tire from the top, does the tread seem to have an "S" curve? If that's the case, and it sounds likely to me, you have a cut cord in the tire caseing. If it was my bike, I'd replace the tire.

Where is 'over here'? If you are in the U.S. you can mail order whatever about any tire you want. Same should be for most industrialized nations. Europe, Austrailia, etc. If you're in the third world, good luck to you.

Unless you just have the tire badly mounted, it sounds like it's bad. Try removing the tire and remounting it. While the tire is off, check iside closely for broken cords. They often bunch up when broken. If you have bad cords, it's off to tire city.

It's hard to know where anyone is without them filling in the 'Location' field in their profile. 4 out of the 6 posters in this thread so far don't have anything for location. Even a rough idea would be better than nothing.

That tyre definitely needs to be removed and replaced - now. It sounds dangerous.

It also sounds like the tire bead may not be fully on the bead lip of the rim. Look at it from the side, you should be able to see a moulded in line in the tire about 1/4 inch from the edge. This should show evenly all the way around the rim. If there is a low spot let out some of the air, enough to push the tire away from the rim edge and get some liquid soap in there for lube. then pump the tire back up and it should pop up on to the bead lip. If not try to help it up there by trying to rock the low spot over with your thumbs.

Resident, unfortunately I have no warranty for my bike. You know, in fact I wanted to buy a new one, but the seller (and other people as well) told me that I would not be able to buy a tire of that quality. I'll definitely buy a new one if there's a chance.

moabrider47, I will try it.

Spoke Wrench, it is something like the "S" curve.

supcom, unfortunately "over here" is in the third world...
Actually one bike technician has told me that it happened because of the tire not being installed correctly the very first time it was installed (I bought it in a second hand shop) and with time its shape has totally changed, therefore now I can do nothing to correct it. Can it be the case?

MediaCreations, that's where I stand too.

Rev.Chuck, I can see a moulded in line, and it doesn't go evenly (at some place it disappears under the rim edge at all!). But I think it will not come up itself, unless I force it to do so. This tire has probably been in such state for more than an year or so. I'll try to do it anyhow. There's no harm in trying.

Try the soap, with that the wheel might pop on its seat when you inflate it to its max pressure. If it does not, force it with your fingers like you were trying to dismount it.

Sounds more like a broken belt in the tyre carcass to me. If the bead is seated perfectly ALL the way around, then the tyre is no good. In fact, it is dangerous.

OK guys. Thanks. I'll try to get a new tire.