# A small bump on the top of my rear tire



## kreyszig (May 2, 2006)

I have noticed that there is a small bump on my rear tire. I always put 120 psi in my tires. I don't think it has been pinched (I have not hit any pot hole and I almost stop when I have to cross rail tracks). I have less than 100 miles on these tires. The rim (Mavic Ksyrium Elite) is true and the tire does not seam to be damaged from outside. Thanks!

1) What could have caused that? 
2) Could the tube be the problem? 
3) Is it dangerous to ride my bike until I fix that?


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## John Nelson (Mar 10, 2006)

Depends on what you mean by a small bump. If the whole tire is bulged a bit away from the rim, then your tube is probably pinched between the tire and the rim. if the bead is firmly seated, then you may just have a defective tire.


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## brianmcg (Oct 12, 2002)

kreyszig said:


> 3) Is it dangerous to ride my bike until I fix that?



TIRE GO BOOM!!!


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## kreyszig (May 2, 2006)

John Nelson said:


> Depends on what you mean by a small bump. If the whole tire is bulged a bit away from the rim, then your tube is probably pinched between the tire and the rim. if the bead is firmly seated, then you may just have a defective tire.


Yes the bead is firmly seated. The bump is about 1-2 mm high. So the tire would be defective, not broken?


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## terry b (Jan 29, 2004)

kreyszig said:


> I have noticed that there is a small bump on my rear tire. I always put 120 psi in my tires. I don't think it has been pinched (I have not hit any pot hole and I almost stop when I have to cross rail tracks). I have less than 100 miles on these tires. The rim (Mavic Ksyrium Elite) is true and the tire does not seam to be damaged from outside. Thanks!
> 
> 1) What could have caused that?
> 2) Could the tube be the problem?
> 3) Is it dangerous to ride my bike until I fix that?



More than likely means that something has broken the cords in the tire. Perhaps a puncture. You now have a weak spot. One of two things will happen - it will continue to get worse and the cordage will start to wear through to the surface (this happened to one of my tires once on a long ride) or it will just blow up unexpectedly when some additional shock allows the tube to work its way through.

Time for a new tire.


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## MikeBiker (Mar 9, 2003)

I had a tire with that problem and it got worse over time. It had broken cords. Replace it before it gets worse. Tires should be round, bumps early in the life are manufacturing defects. If you have a receipt, try to get it warrantied.


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## kreyszig (May 2, 2006)

MikeBiker said:


> I had a tire with that problem and it got worse over time. It had broken cords. Replace it before it gets worse. Tires should be round, bumps early in the life are manufacturing defects. If you have a receipt, try to get it warrantied.


This tire came with my bike. This is a Specialized tire on a Specialized bike... I will bring the tire to my LBS and see.


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## Argentius (Aug 26, 2004)

yeah, you should. If it's a little "pimple" in the tire, that means the integrity of the casing is compromised, and so it's not holding the pressure as well.

It's possible to cause this damage within the first 100 miles of use, just by running over a piece of gravel the wrong way, too. Take the tire off and inspect the inside and outside of that area for cracks; which side it's on should tell you something.


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## kreyszig (May 2, 2006)

Argentius said:


> yeah, you should. If it's a little "pimple" in the tire, that means the integrity of the casing is compromised, and so it's not holding the pressure as well.
> 
> It's possible to cause this damage within the first 100 miles of use, just by running over a piece of gravel the wrong way, too. Take the tire off and inspect the inside and outside of that area for cracks; which side it's on should tell you something.


I have inspected the outside of the tire and there is no crack or any damage around that area. I remember to have heard a poping sound yesterday. I guess that was a cord breaking. My bike (and tires) didn't even have 30 miles when it happened. I was riding on a smooth paved trail when I heard that sound.

However there are a couple of small (~1/8" long) cuts on my tire (that are far from the small bump). Should I do something about these or they are part of normal tire use?

This morning I went down hill @ 40+ mph. I guess I should inspect my tires more carefully the next time!


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## terry b (Jan 29, 2004)

kreyszig said:


> I have inspected the outside of the tire and there is no crack or any damage around that area. I remember to have heard a poping sound yesterday. I guess that was a cord breaking. My bike (and tires) didn't even have 30 miles when it happened. I was riding on a smooth paved trail when I heard that sound.
> 
> However there are a couple of small (~1/8" long) cuts on my tire (that are far from the small bump). Should I do something about these or they are part of normal tire use?
> 
> This morning I went down hill @ 40+ mph. I guess I should inspect my tires more carefully the next time!


Surface cuts and slices are no big deal until the tube pops through. And then you have a flat. They're part of regular use, but you should keep an eye on them and make sure they don't get down into the casing.


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