X3 run flat tires are easily available in US, one of the sources is Costco with tire life time warranty.
So in my view, one need to buy 4 tires max from Costco at $900 approx for the life of the tires and thus it's uneconomical to go for expensive BMW plans.
If you are desperate for protection, drive your brand new X3 to Costco, buy 4 tires and sell your X3 tires on eBay
. This way you will save substantial amount.