Join Date: Jan 2007
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Have you checked the TPM valves are nice and tight against the rim. IIRC they are bolted on, and if this is a little loose it can cause leakage.
I must say though you've done well to have no problems with them after 7 years.
Currently in dave_mezza2006's garage:
2014 Vauxhall Astra Limited Edition 1.4 16v VVT Turbo