The M3 GTS prototype uses them.
BMW M engineer said that they have to use them because the cups don't meet some environmental regulation (and it would be good to stock cups because they won't be produced in the near future - what shimmy has done basically).
I had a set off them for the M3 last year good value for the money but they are old stock and the rubber's a bit hard not quite as grippy as a cup and they only had one side,so your running two tyres the wrong way
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