Tyre bulge

[neil_p]

I have run 26x1.5" Pasela tyres for ages with no problems. A recent switch to 26x1.25" has led to this bulging...



Any ideas what might cause it or how to solve it? Tubes are 26x1 1/8 to 1.3"

Cheers

[JimK]

In my experience, that kind of bulge is just the tire failing to be seated properly when it got mounted. I just deflate the tire & try to get the bead even all around the rim - i.e., at the spot on the other side of the wheel, 180 degrees, the bead is probable too deep in the well, which lets the bead bulge out on the other side.

Sometimes I have to go through the cycle a few times, of deflate, fuss a bit, and reinflate, before I get the tire on the rim nice and pretty.

By the way this kind of bulge is a bit dangerous. The tube can poke out there. I had a tube do that and explode... the neighbors up and down the street came out their doors to see whom got shot!

[Danneaux]

Hi Neil,

I agree with Jim here, especially given the location.  I believe the tire bead has not seated properly, and may indeed be riding on a wad of tube, which would be a Bad Thing.  It is easiest to capture a bit of extra tube between the bead and rim seat right at the valve, owing to the extra material used to fasten the valve to the tube.

The rim tape may be dislodged a bit, too, causing the tube and casing and bead to be unseated.  This is far less likely with a cloth or plastic tape, but is not uncommon when a strip of rubber is used,

This kind of bulge can also occur when the bead is no longer captured properly at the rolled-over edge of the tire casing.  The wire (or Kevlar, in the case of a folding tire) can escape and cause poor seating.

In any case, I'd let some air out sharpish and then carefully reseat everything.  Just be careful not to ride the thing until it is resolved.

Best,

Dan.

[neil_p]

I'll have a play over the weekend. Rest assured, the tyre was almost entirely deflated when I took the picture, and will not be used until the issue is solved.

[julk]

Neil,
That looks like a classic case of the valve base stopping the tyre beads seating.
With the inner tube deflated, you must push the valve right up into the tyre whilst seating the tyre beads in that area, then pull the valve out as far as it will go and it should trap the tyre fully seated on the rim.
Julian.

[neil_p]

By jove, I think you've got it! It always happens by the valve, and indeed this happened in the same spot with the two Paesla TG tyres on my wife's bike (different size though). Thanks... I'll give it a go. My back wheel is in the kitchen at the moment.... so she'll be very pleased to see it returned to the shed!

[neil_p]

Thanks julk, it worked a treat! Not sure how I've never seen that happen before, but good to know how easy it is to fix.