I'd change it now... As soon as tyres start to show this kind've wear... we change - if not before.

As for riding til it blows, please don't take offence - but that seems irresponsible to me.

What if it blows on a downhill corner? Who among your family gets to pick up the pieces?

What if it blows on a busy stretch of road and you lose control and go under a truck? How will the truck driver live with himself?

What if it blows when you are riding with a pack of friends? Are you gonna feel ok about the crash you may cause?

I'm sorry, Deb, this is not intended as a flame, but you really need to consider your own safety and the well-being of others (not to mention the possible damage to your steed...)

Biking should not be about screwing the lass cent out of every piece of equipment... it should be about having fun safely...

I hope you change your tyre.