Brittle tyre valves

[Afsimba]

So was out for dinner few nights ago and the Tpms threw up an underiflated rear right tyre . Checked on system and no biggie lost few lbs at most kept screen on to monitor further but dropped no further ! Was gettin late so left till next day to investigate ! Unscrewed dust cap and the whole threaded area landed in my hand in several bits only thing left was the little pin in the middle that depresses . Car only covered 9k miles always garaged and 65 plate no sign of corrosion on em just basically brittle and in bits

[harrier]

Perhaps water got in under the dustup, froze, expanded and shattered it? I take it the dust cap was plastic? - have had "Audi" logo-ed metal ones in the past which caused rapid electrical corrosion of the valve and which wrecked the thread.