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A mate gave me a bunch of 27.5 stuff as he's going full 29.
One of the tyres is a Magic Mary 2.5 and is in great nick wear-wise.
However, in the side wall, just above the bead there is a slight bulge. It is about the size of a baked bean (albeit a squashed one). It moves like a surface blister to the touch - same movement whether inflated or empty and off the bike. There is zero damage showing on the inside of the tyre (the carcass proper).
It seems like it is just that the surface layer has come away in one small spot.
So would STW ride it (tubeless on the rear of a hardtail)?
My concern, such as it is, is that this will obviously be a magnet for scrapes etc and could rip this blister thing. I don’t think there is an increased risk of total failure - but happy to be told otherwise.
WWSTWD?
I'd bin it.
So the bulge is not under the inflation pressure of the tyre.
The carcass (structura part of the tyre) is fine.
I'd ride it
I have fixed some such sidewall-damaged tyres by gluing a big patch on the inside. I used a plastic mesh meant for fixing pvc equipment (like inflatable boats) with generous rubber glue and let it dry properly. Rode for years after fix, and that one had an actual slash all the way through the tyre.
I've just gently slit the blister with a craft knife, squirted a load of superglue in and given it a good press (head of a cricket bat mallet in the tyre and a dowel on the area with my weight leaning on it) for about three minutes.
You can only notice glue residue now, no failt is visible.
I'm currently running another cast-off tyre in the rear - I'll see what happens when I inflate it again...
Ta.
Superglue isn't ideal for tyres. It dries rigid, can either crack or further degrade the material it's attached to. There are other glues that allow for flexing.
There was a few cases of one manufacturer tyres developing blisters in the tread, I think it was tiny leaks in the carcass that were caught by the outer rubber which then inflated into a little blister. You could patch it on the inside if it keeps reappearing.
I'd bin it. But I did give away 5 virtually brand new and 2 brand new tyres last week
I'd do what fenderextender suggests except with either tyre repair goop or a flexible glue like E6000 or shoegoo. I think Al's spot on, the actual carcass of the tyre is probably fine so it's really just a bonding issue. Probably less "damaging" or risky than a repaired puncture