looking at a 525 d m-sport with 172 rims, are the tyres run-flats?, according to the bmw website you get the space saver spare with these wheels,

also do these models have the "M" button and what does it do? i sound like a newb lol

 

Not sure about the land of rain and misery, but here in the states the 172's come with regular tyres, not run-flats.

 

i guess they must do here to if the space saver spare is inlcuded, the spare wheel is an option here if you have runflats

chears

 

Yes the 172s are non-RFT and come with the space saver spare included with the option. The M button is something that is present on the M5 (possibly M3 and M6 as well although I'm not sure). There is no M button on the M Sport cars. Just for information, the M button on the M5 unleashes another ~100 bhp and does a few other things as well.

 

the space saver does not fit correctly so you end up with the mobility kit unless
you want to butcher the boot and 'make it fit'! Had mine fitted at a dealer who
then had to refund for the space saver, even they seemed surprised.

 

I don't think this is an issue if it is a factory 172M wheel options as the space saver comes fitted in the boot perfectly. Could it be there is some kind of insert that the space saver fits into?

 

perhaps the factory boot assembly is adaptable as you say, just not on my 05' m sport which came with runflats
therefore not spec'd with this option. They genuinely did try but didnt want to dismantle anything, although they are generally pretty clueless.