Should I be able to peel off a glued tire patch? One of the things that I've noticed with the low-cost tube patch kit that I bought is that I'm able to catch an edge of the glued patch with my knife or fingernail and peel the patch off the tube like a bandaid.  While handy for repatching, it doesn't give me a whole lot of confidence in this kit.

Shouldn't a glued patch be essentially so welded to the inner-tube that it's unable to come off through any normal means? 

** This is a cheap kit with glued patches (ie, separate glue and patch, not a "glueless" patch)
No, you shouldn't be able to peel a patch off, regardless of if its a glued or glueless patch.

Confirming that this is a wet-glue patch that has failed to stick?  Possible causes for failure of a patched tube


You didn't clean the tube properly
you didn't buff the tube properly
There is a ridge in the tube which is in the way, has left a tunnel of weakness under the patch
its a latex tube not a butyl rubber tube
The patch was cheap and/or nasty, or possibly old, or damaged by heat/sunlight.
The rubber cement was cheap (watered down or just not very good)
The cement was really just a glue (cheap again)
The cement was old, more-so if it had been sitting around open for a while since your previous puncture fix.
You didn't wait long enough for the cement to dry - 10 minutes is my normal wait time.
You didn't spread the cement out far enough on the tube.   It should make a wet area bigger than the patch.
You stuck the patch on upside-down, so the wrong side was out
When unpeeling the patch backing you touched the surface, and left finger oil or other contaminants enough to interfere with bonding
You didn't press the patch on firmly to the tube.  I use a tool as pictured below, but a round coin works well too.  You have to roll it over the whole patch, back and forth over and along the edges
Did you inflate the tube outside the tyre?  Without restraint, the tube will stretch, which causes extra strain on the cement.


These aren't likely to be the cause of the patch peeling off


You missed the hole completely, or far enough so that it was to the edge of the patch
The hole is too big to be patched.  Cuts over 5 mm generally mean a new tube, and holes more than 2 mm in diameter tend to not patch so good.


EDIT: Other points I missed
 * patching in the rain or dampness - water/cold stops the cement from curing as quickly, and being wet makes you hurry.

Personally I'm not very good at punctures, I have a success rate of 2/3 repaired okay if I start patching a tube.

In a pinch, I've successfully cut a round piece of spare innertube, buffed and glued its innerside, waited 10 minutes and slapped it on the buffed and glued inner tube.    It worked perfectly and is still on the bike today.

I know yours isn't a glueless patch, but for completeness:

By comparison, glueless patches are really glorified stickers.  They don't bond to the rubber of the tube as well as one with vulcanising fluid/cement.  But they're also a lot quicker to buff, slap on and ride more.  Their maximum pressure seems to be lower too, so bad for roadies on 100psi, workable for MTB on 30psi.