LarrySellerz

Hey guys, my road bike developed a "bulge" on the back tire near the valve stem. I have seen similar in tubes, but not when inside a tire. Reinflating does not resolve the problem. Have you seen this, and is the problem with the tire itself or the tube? I am thinking there is a thin part of the tire. I noticed the problem when a subtle "bump, bump, bump" started which normally to me means it is about to blow. Problem just developed today, I would have noticed it before.

Polaris OBark

Do you have a photo?

badger1

Tire pooched. Get new tire. Install.
/thread

79pmooney

Tubed or tubeless? If tubed, did you push the valve in after mounting the tire to ensure it was inserted full beyond the tire bead? This sounds like the tire sitting on the valve/tube interface instead of the seat on the rim. Do nothing and this is the case and this will bump away until the tube gets tired there and flats or perhaps the bead will be lifted off the rim and the tube will blow in grand fashion.

LarrySellerz

Tubed. All of the tires I can find immidiatley are pretty beat up except for a 38 knobby and this other smooth one that says "Use on hooked rims only" and I think I remember it screwing with me like a year ago. If I have to live with this tire, what pressure do you think I should run it at given the bulge? Road bike 25mm. thinking about going really low, like 40. Trying to find another tire

79pmooney

Deflate, push the valve stem in, pump up and report back.

3alarmer 

.
... check the bead, and see that it is still well seated on both sides of the tire near the bulge. The other reason you get a bulge in a bicycle tire is when some of the fabric threads tear, in one of the underlying layers. If that is what's going on, there is no "safe" lower pressure at which the tire will not soon fail. When it does finally give out, it will be along some roadway, in the dark, and you will have no spare tire to replace it with. So you will need to walk home, carrying your bike. Hopefully, the busses will still be running.

Trakhak

Fabric threads can also be cut by a brake pad, either because the pad is adjusted too high or because a dip in the rim (from, e.g., hitting a pothole or a curb) brings the tire low enough to contact the edge of the brake pad(s).

Polaris OBark

Fat chance.

LarrySellerz

This wheel has some deepness to the rim, and I remember trying to install another tube with a stem that was barely too short and having to push it hard, maybe that weakened the tire. Some threads started popping out near the bulge, like it is seated correctly and the threads are coming from the face that meets the ground not the sidewall. I first noticed something after throwing throwing the bike in the back of a pickup truck this morning, maybe it hit something sharp in the bed of the truck? In any case its clearly getting worse so I'm replacing it, the "hooked rim" tire didn't work so it went back in the pile, and unfortunately I couldn't find another tire so I have to go with this knobby 38, and this 38 is kind of throwing me off.

For one, the pressure is called out in kilopascals, is this some gravel thing or something? It also calls out a direction of rotation, which I thought was kind of absurd, is that about the tread? It can't matter much can it? Also the tire just looks absurd on the rim, the wheel is kind of aero and measures 21.14 mm and the tire measures 37.09 mm, for a ratio of about 1.75:1. Is that pushing the limits of how big of a tire can fit on the rim? When first inflating, the tire did not properly seat on the rim even thought I was being careful (had my safety glasses and earplugs in) and the second time I got it to seat, but I wonder if it is liable to blow off the rim in the future or now that I got it seated it should be OK.

edit: tire is rubbing against the brake housing when fully in the dropouts, I backed it out slightly and it clears. Still plenty of clamping force and it’s straught enough that the shifting is fine, so I’m not TOO worried about this.

3alarmer 

genejockey 

shelbyfv

The tire is really just needed to protect the tube. Don't obsess over a little irregularity if it holds air. Low pressure and some hard cornering should smooth things out.

Chuck M 

Do as 79pmooney suggested. While you are at it, you can try moving the part of the tire that is bulging away from the valve stem. If the bulge moves, condemn the tire. If it is still at the stem, do as 79pmooney suggested until you get it right.

Eric F 

Some straight answers...
- The bulge is most likely a sign that the sidewall has an issue, or the bead isn't properly seated. When it completely fails completely, it's likely to do so catastrophically, and possibly at a time that is extremely hazardous to your well-being. If it's a worn sidewall issue, the correct choice is to replace the tire ASAP. If it's a bead issue, deflate the tire, reseat the beat, and reinflate the tire.
- Reducing the pressure to 40psi in a 25mm tire, in an effort to minimize the bulge issue, is a recipe for wrecking your rim (especially since you are a bigger fella), which is a lot more expensive to repair/replace than a tire. This is also likely to accelerate the damage to the tire sidewall.
- Rotational direction is related to tread pattern.
- Kpa is not a "gravel" thing,

Based on your history, I'm not expecting you to make the best choice. I do expect you will generate some wonky justification for why your solution/work-around is better.

Good luck, Larry. I sincerely hope you don't get hurt.

LarrySellerz

The tire is garbage, big hole wanting to form. Honestly the pressing question is is it better than the mtb tire that is 1.75 times the width of the rim and not fully in the dropouts. clearance is clearance, as they say

Polaris OBark

Why not purchase or shop-lift a new tire?

LarrySellerz

This happened at work, I pulled tires off of abandoned dead bicycles but its hit or miss

Polaris OBark

I have several 50% worn Barlow Pass tires I have been saving as spares. 700C x 38mm. Do you want them?

LarrySellerz

I think it’s neither, since I made this post “threads” started coming out in the “middle” of the tire as if there is damage. Still definitely something that will suddenly deflate, not something slow, lol.

Polaris OBark

OK. I've got several. Is 38mm ok, or too wide? I've collected a lot of data at SSRL over the years.

LarrySellerz

I have a soft spot in my heart for the “cheap hybrid” like the Giant Escape 3 or other clones, and they come with 38. Think it’s a great size. This one doesn’t seem to fit on my road frame very well, but beggars can’t be choosers. Anyways I have a giant escape 3 that I need to fix so yeah 38s would work great.

edit: I thought I remembered giant escapes had 32s but google says 38, maybe it’s one of those Mandela effect things like the barenstein bears
edit2: Is there a rule of thumb for a ratio of tire width to rim width that you don’t want to exceed?

3alarmer 

Polaris OBark

I'm going to send you 2 used Barlow Pass 38mm tires and two completely new WTB 32mm tires. I have them in a box and will let you know when I get a chance to send them.

Peruano

Bikes hung on the back of automobiles occasionally dangle close enought to exhaust pipes to suffer from exhaust. Result sidewall damage and bulge. Watch your dangle.