My agency's contact at FHWA says that the new UA delineations, and all the Urban-Rural determinations for Blocks, will be published in "August or September." (I’d wager on the over side -- not the under.)
There's not a Census designation of urban or rural tracts. But it would be easy to summarize the block level numbers into tracts: X% of the population is urban, W% of the land area is urban, etc.
Cheers,
Todd Graham