This spring I mounted a MT21 Trials tire with a Bridgestone Ultra HD tube and dual Litelok rim locks. I run 6 - 6.5 pounds of air and love it. Recently I noticed a bumping feel like the tire was out of balance but it didn't do it from the beginning and I never had any wheel weights on it that could have fallen off causing a difference in balance. With it up on the stand I spin the rear wheel and saw a noticeable "bump" in the tire where it is about 1/4" taller than the rest of the tire. It only protrudes maybe 1" in length of the circumference and it's real close to where the valve stem is. The tire is still seated properly on the bead all the way around. Is there any possibility that the tube got "bunched up" as I noticed that the valve stem is slightly slanted as if the tube is sliding in the tire. I have the stem lock nut all the way out so the stem can move as instructed. Do I have to take the tire off to see what the problem is or can I let all the air out and possibly realign the tube?:
Although I've not experienced it, one theory is that tubes will bunch up and walk around the tire, which causes the tube to eventually leak. I am extremely lazy so if it were me I'd let the air out of the tube while the wheel is on the bike and see what is going on. You could always take the wheel off if needed.
Was the tire real tough to put on? I have seen this with a broken bead or broken ply is why I ask. I doubt that the tube has caused this but coffee's method is a easy way to rule the tube out. Just take the core out and let the tube settle. If this does not work you will have to take the tire off and see how the tire lays off the rim. Mark the area first and push on the tire and see if you feel a soft spot.
Hopefully I'll be able to give it the "once over" tonight. Thanks for the suggestions, and when I figure it out, I'll let you all know.
Luckily the easy way out worked just fine. I took the core out before I left for work this morning and at lunch spun the tire while pushing the center of the tread in towards the rim as far as I could. Then I grabbed the stem and pulled it back straight (sort of prying it a little) to slide the tube inside to get everything re-aligned. With the core out, I took the air compressor and pumped it full of air/let it bleed 3-4 times to seat everything again. I put the core back in and pumped it back up to 7psi and spun it....beautiful Maybe running such low pressure (6 - 7 psi) allows the tube to eventually get bunched up like that, but I like running real low pressure to get the benefits from the tire, so I guess this will just have to be a routine maintenance thing for me.
I would take the tyre off and have a good look at the inside tyre side wall and the tube. If ok I would apply a lot of baby powder to keep the tube from sticking and reduce friction. Distorion at 6-7 psi is not normal. It could let you down on the trail 20 miles from your trailer.
