Think this problem has been discussed some time ago.
My Pirelli run flats have shown cracking of the tread since new, July 03 S. Still have the original tyres on he car as it's only done 6k. The cracking seems to be on the tread itself rather than between the tread and doesn't seem to cause any problems. I noticed the cracking after about a week of owning the car so after 3 years they are still inflated anyways
