At the same time I was wondering what people's experiences were with DT 535 rims for bicycle touring. I have a Shimano XT 737 hub and paired with a DT Swiss 535 with an ERD of 540 would give me 261 mm on the L and 259 on the R.
A crucial part of determining correct spoke length for wheel builds is an accurate "Effective Rim Diameter" (ERD), a concept that is reviewed in this article.