Just to resurrect this post with my own experiences. My 2013 6 Sport Nav had the same issue. 3 tyres were the O.E Bridgestones, the 4th was a cheap budget put on by the dealer when I bought the car.
TPMS was driving me nuts and would come up every journey. I replaced all 3 Bridgestones with nearly new Dunlop Sportmax. Still TPMS going mad. So replaced the budget with an equivalent Sportmax so all 4 were the same make and similar tread wear......guess what...No TPMS warnings. I've had 2 warnings since, one was I was driving along the dual carriageway and went through quite a layer of hail stones on the road surface, I'm guessing the tyre temperature dropped sufficiently quickly to make the system think it was losing pressure. The other warning, I've no idea what triggered that one. So one spurious warning for no reason in 4 months versus at least once every time I drive the car...