Well, this thread convinced me to do it!

I went with 265/60/18 Falken Wildpeak AT3Ws on style 69s. WOW, they are heavy tires. Made the stock 19's with 285s feel like racing wheels.

They fit fine, plenty of room around the tire with zero rubbing. I'm glad I did not try to squeeze in 265/65s or 285/60s. I only test drove a few miles but the experience was... interesting. It makes the X5 feel very truck like, but not in a horrible way. There is effort needed to turn at low speeds, and you can definitely feel the unsprung weight added. The fastest I got to was 50mph so I'm curious to see how high speed driving is.

Ride height is noticeably higher - I don't think I'm going to do the lift kit anymore, at least not right away. Especially after hearing Ragnarok's experience (thank you guys for the reviews). The Wildpeaks stood a bit over 1.5" taller than the 19" stock tires, and it feels like my X5 is right around .75" taller overall.

Will post more pics of the full car in the next week or two.