If its the standard MB underinflation warning system it relies on the ABS sensors picking up on the reduced radius of a tyre going down- so nothing to do with the tyre. Technically its likely to be the same tyre carcass but rumour has it MO tyres have a slightly different tyre tread compound [ softer] to give their new cars better than average ride quality possibly at the expense of mileage wear potential.
C350 CDI Sport Plus, RX8 replaced by Mazda2 (wife's)
I thought the MO tyres were the same as standard but Mercedes were more strict on manufacturing variations so I'm surprised the ratings differ. But maybe I'm just gullible!
ML350Cdi BE now replaced, E220 2013MY just for a bit.....
Some tyres that are specc'ed as OEM have subtle differences, it could be that the rain channels are slightly closer/smaller to gain something in either dry grip or sound propagation over the standard tyre, this is true of some Audi specc'ed tyres that are RO1 (Quattro spec) rather than the normal AO spec.