My rear 50 mz goes down from 32 to 20 overnight, caused a nasty lift off overstear moment.
2/3 worn- would it be wise to seek repair

 

Repair.

Otherwise 2 new tyres.

 

If the puncture is found to be towards the centro of the tyre, I'd definitely repair. If it's towards the tyre wall, bin it and get two new tyres IMO

 

the limit is around 1-1.5x the width of your thumb, measured from the edge of the tyre.
if your thumb covers it, it's unrepairable. if its anywhere else on the tread area then it's repairable.

i say get it plugged. wast of 1/3rd of a tyre!!

 

Repair if you can