[cdmulders]

That tire needs to be replaced. Because it is xDrive, it might also make sense to have both front tires replaced, assuming the old ones are fairly worn.

I'm running 245/40/19 and 275/35/19 tires on my stock xDrive with no problems. For a 20" wheel, 245/35/20 and 285/30/20 are actually a better fit vis-a-vis diameter and circumference. Check out this link. Nevertheless, because your rear wheel is only 9" wide, and as has been said before, you probably cannot go with a 285mm wide tire, so stick with 275mm per your original setup.

Depending on where you are with negotiation and if you do plan on replacing these tires with Michelin P4S or similar, then I'd probably ask for a bit more off of the price of the car vice asking them to replace the tires, and then replace all four with the Michelin non runflat tires. The ride improvement and handling on Michelin tires (I have Pilot Super Sport vice the newer P4S) is very noticeable.