max weight that the shimano Rs400 can carry ?
Shimano RS400 is pretty old now - I know my 1998 frame had the wheelset new.  

Here's a photo of my rear hub.  I can't show the front hub because that was replaced with an WH-R560 by a previous owner.   Why it was replaced, I don't know - it was either a speed optimisation or a failure where a new wheel was better than fixing the original.



Generally speaking, touring wheels are built for strength not speed.  So touring wheels should be at least 32 spokes on the front and more would not be bad.