Dunno if I spoke too soon about the age of my front Metzeler Z6 tyre, but appeared to have a bit of a slow puncture, which got progressively worse this week, until Wednesday when I had to pump it up three times in one day...
Anyway, popped by some garages, none had that size in stock (is it really that unusual?!), got a Z8 ordered for today. However yesterday, I pumped the tyre up again and noticed it was leaking like mad from the valve - oooh hello? Quick Google reveals it may have just been a dodgy valve core. Popped by Halfords, got a valve tool and packet of spare valve cores (£7). Tightened up the existing valve to begin with, turned out it was super loose. Tyre now appears to be hold pressure absolutely fine!
Gonna still pick up the new Z8 tyre mind, as my current Z6, although still got a bit of life left in it, the centre treads are down to about 1.5mm. Rather play it safe, than have a slip just for the sake of eeking out a couple more months out of a tyre.
Moral of the story: If you've got a flat tyre or tyre that needs pumping up often, double check the valve is tightened up enough!