Run-Flat All-season Tires

How do these function?
Are they Special Tires? In other words, is the "run-flat" feature a function of the specific tire, or rather something to do with the wheel/rim?
Will having this option on my BMer limit the types of tires I can put on the car?
Will I there be compatible snow tires i can put on these rims, on a 2003 330XI if I want snow tires?

{In 2003 the Sport Package comes standard with Run-Flat All-Season tires. To avoid the tires, one would have to miss out on the sport steering wheel AND the sport seats: not a good option, i.m.h.o.}



>>Also, Does anyone know if the Park Distance Control can be turned off and on at one's whim? Is there a volume control on it? Does it override the radio/stereo, or compete with it?<<<


Thanks for any information.

I"m in the final stages of ordering a 2003 330XI. Just waiting for the residual value figures to come in on the 2003's so I can get some competitive bids for my lease.

Jeff in Boulder.

I'm sorry, I forgot to look before I posted and see there was another thread with the same topic. Sorry.