XT M775 Wheelset
I just bought a set of Shimano XT M775 Wheels. They are tubeless. I just want to make sure that I do not need anything to put on the rim in order to seal them. And, do I have to adjust my brake calipers because I am switching from the 6 bolt disc pattern to the centerlock?
If you are asking if the rims are air-tight, then yes they are. Regardless, you should be using some sort of sealant even when using tubeless tires as some air will escape through the tire/rim contact. You can run tubeless tires without any sealant at all, but you will have to pump up the tires often. At least that's what I found when using Racing Ralphs on my set of XTs.
As for your question regarding the need to adjust your calipers, that depends on how closely your old hubs were designed/manufactured to 6-bolt standard. In my case I switched from Bontrager hubs using Hayes rotors to XT hubs using XTR rotors and did not have to touch the calipers.