Hi Prank, congrats on the purchase! Like you, I’ve recently wandered into BMW ownership with an E90 320i. Your right about the runflats, I’ve had the same experiences with them. Luckily the previous owner only just replaced them because I will not be buying them when the time comes around, I just can’t justify the price! You can get runflat “repair” kits(previous owner got one)but it’s not advisable to do so haha