The TPM detected a pressure drop in one of my tyres a while ago.
Having manually pressure tested all tyres I found that the rear nearside was slightly down.
Since then I've been losing around 4psi per week and I took it to a tyre fitter a few weeks back but unfortunately they couldn't detect any puncture and stated that I should just keep an eye on it. So I upped the pressure back to 34PSi to match the other one and left it be.
Three weeks later (yesterday) I carried out a check and found it to be down to 22PSi. I'm amazed that the car still felt ok to drive whilst being so low on pressure! I couldn't feel much difference in handling.
So where do I go from here? I have about half tread-life remaining and a puncture which cannot be detected.
Not the end of the world and I'm sure it won't blow-out but I'm keeping the speeds down just in case.
I'm not bothering with re-setting the pressure monitor at the moment as enevitably it beeps within a few days to tell me what I already know..