I just bought a used bike and one tire has a slight bulge by the valve. was it just installed wrong? it's brand new, so maybe it got twisted or something? any thoughts? I didn't want to go through the trouble of taking it off if it's no biggy

I currently have this on the front tire of my hardtail, which gets no use besides being on my trainer 247. I have taken the tire off and even installed it on another rim with a different tube with the same results. Chances are something inside of it is blown, and I would not advise riding on it if you take it entirely off the wheel and when it's reinstalled it still results in having the bulge.

a bulge in the tire is a sign that the casing underneath the rubber has failed or is beginning to fail. deflate and reinstall the tube and see if the bulge is still there. if so, then it's time for a new tire.

This. Don't take chances with dodgy tyres, especially if it's on the front.

Time for a new tire.

Absolutely correct. /thread

It's possible that the tire is just not seated correctly. Deflate, make sure tire is seated evenly. pump it up part way, check for even seating. If good, pump & ride. If still suspicious, toss it.

Most likely the bead is not seated. The tube is thicker at the stem, making it more difficult to get the bead all the way down. Most tires have a molded in line parallel to the bead that you can use to check if the bead is all the way down. The tube may also be pinched between the tire and rim. That can cause a lump in the tire. Let the air out push the tire over to each side. You should be able to see the rim strip and see that the tube is not in between the tire and rim.

If you did pinch the tube, it will eventually wear through and pop.

i took it apart just now and it seems like one half of the tube was far over on one side (like maybe a manufacturing defect) I think I fixed it as o pumped it up a bit with my mini pump. I'll pump it fully later and see if the bulge is gone. thanks

All tubes have variations in thickness that causes bulges here and there when inflating by itself. When encased inside a strong casing like a tyre, it will form itself into the same shape as the tyre. What typically happens is people start and stop installing the tyre at the valve. This causes the tyre to pinch the tube between the tyre and rim-edge. So it's best to start installing the tyre far away from the valve and go over that area along the way. Then after the tyre's installed, push the valve into the rim and tyre to make sure the tube is fully inserted inside the tyre. Then, pump up the tube one or two pumps to inflate. Center and adjust the tyre as necessary so it's fully seated all the way around and is concentric around rim. Then inflate fully.