In 25 years I have only ever seen this the once, when it happened to me. I was flagged down by a passing motorist on a motorway in Holland.
I stood and watched it, it was fascinating, the balloon got bigger and bigger and then went “BANG!”, although the tyre stayed up 
Anyone else ever seen this happen to a tyre?
Yes on the way to Felixstowe, looked in my os mirror appraching the last roundabout on the A14 and saw something strange on the rear os tyre of the trailer so pulled over to have a look in dock and had exactly the same fault, bloody Friday as well and had to wait2 hrs for tyre fitter to replace it. 
When there is a bulge like that in the tyre it is definitely time to hide behind something far away.
Never had that but this English driver thought there was nothing wrong at all with this-
Harry Monk:
I wonder if LASONIL would help 
Those illegals are finding evermore ingenious places to hide, this one should have tucked his head in a bit more though.
seen that a few times mainly on agricultral or telehandlers on building sites,where the tyre has been nipped by the rim and something hard like a rock or kerb…tyre fitters usual way of deflating is let the valve core out and once tyre is deflated spike the bulge with a 4 foot long bit of wood with a nail in the end(thats what i kept in my van some use there knife on a stick and brave/foolish use a screw driver while standing beside the tyre)
I have seen a tyre do that, although my worst experience was with a elaflex tanker delivery hose. I was tipping Glucose in Muller Rice and the pipe started to do that. I stopped the pump and went for the customer valve, just as it burst.
You try stripping naked in minus 3 temperatures to climb in your cab for new clothes, especially in a busy food factory 
had a drive axle tyre do that last year
it was fine when i did my daily walk round checks that morning, but, half an hour later, there was a bulge on the side of the tyre, not quite to that extent, but there all the same
the tyre fitter was duly called and swapped the tyre, the bulge on the inside was bigger than the outside 
Wheel Nut:
I have seen a tyre do that, although my worst experience was with a elaflex tanker delivery hose. I was tipping Glucose in Muller Rice and the pipe started to do that. I stopped the pump and went for the customer valve, just as it burst.You try stripping naked in minus 3 temperatures to climb in your cab for new clothes, especially in a busy food factory
Could have been worse Malc! In the summmertime with all the wasps about!
Had something like that on a CAT 980 loading shovel tyre in Shap quarry,blebbed up enough to dislodge mudguard,it was parked up with an exclusion zone,didn’t want to go anywhere near an 29.5x25 earthmover tyre in that condition!
Who do you think you are kidding!
that is obviously a ww2 stormtroopers helmet bluetacked to the tyrewall
Some of you blokes are ■■■■ weak. You could have made it back to blighty with half a dozen like that. 
Ben9:
Never had that but this English driver thought there was nothing wrong at all with this-
Too right…There’s loadsa tread left on that!
bigvern1:
Ben9:
Never had that but this English driver thought there was nothing wrong at all with this-
Too right…There’s loadsa tread left on that!
nowt wrong with that, just needs turning!
man that is some serious kerb crawling
bagpuss:
man that is some serious kerb crawling
Its one hell of a crap driver !