IMO and it is only my opinion...BMW will use any available excuse to get out of an expensive warranty claim, they therefore make it widely known that a change from OEM designed and supplied tyres on a vehicle could impact on the drivetrain of x-drive vehicles. So when you turn up with a transfer case issue they simply say, wrong tyres mate that caused the issue.... goodbye!
From my logic you can't tell me that they produce a different x-drive system for different cars they produce? Okay they may have different tweaks and software in some (M2,3,4,5 cars) but the base mechanicals of the 4wd system must surely be the same?
So, discounting full fat M's, you could some years ago here in the UK order your M140i with non runflats from new, there were also others but I can't remember which so will only use that example You can't tell me that they would have a different transmission installed on the production line because you ordered go flats?
I also looked at some second hand wheels the other day that came off a new M240i Gxx series They were 8.5"x19" fronts & 9.5"x 19" rears but the standard tyre size was Front 245x35x19 and Rear 255x35x19 which puts them just the wrong side of the 1% tollerance and they were PS4S go flats.
That car with more power is going to, by the nature of what it is, put more stress on components potentially resulting in earlier x-drive failings if the tyre issues are to be believed, kind of counter intuitive of BMW to produce such a car then??
In the current trend of building a car with everything already in it, then you paying to switch options on via a subscription, including a power upgrade, it kind of reinforces the fact that multiple use components across various platforms will be used therefore, if they will supply platform 1car 'X' with go flats & platform 1 car 'Y' with run flats the tyres can't be the issue.
To substantiate my thoughts further. Goodyear F1 asymmetric tyres for BMW 5er's are RFT * but also designated MO for Mercedes, you can't tell me that the 4wd systems of both manufacturers are the same?
Personally I have found the SA's in the dealership about as much use as a chocolate tea pot, they are fine if there is a book that tells them the answer but outside of that they are hopeless. I have asked specifics about tyre differences and the specifications but they can't give any supporting technical data to substantiate the 1% tollerance question.
I suspect that their base level advice is to stop someone putting Chinese LinLong rubber on the front and some other Chinese different rubber on the rear, which will be way out of tollerence and thus highly likely cause issues, but if you use * rated go flats, that's hardly likely to be in the same boat.
I'm not a particularly electronic tech savvy person but did read somewhere that in ID 7 & above there is an option in the tyre settings for 'individual' and if you put your individual rear tyre size in and drive off it will disconnect the 4wd system and calculate something to measure the fronts, if there is an issue you would like to think it would flag it up straight off and not wait until the transfer case disintergrates!
As for me I'm off for some premium brand go flats and likey * rated...Happy motoring
