my mate just had the run flats dilema on his 118d. He fitted non runflats, 1 week later he calls me up, got a burst tyre and no jack, no spare and the tyre is off the rim so the can of foam stuff wont work lol!!

11pm I had to go and get a trolley jack and luckily for him had a spare bmw alloy and get him back on the road.

If you do fit non runflats, I would by a space saver and chuck it in the boot.