Again, internal or external?
30mm internal (Like the DT XM 481’s) usually mean an external width of around 34-35 mm are are pretty damn wide, you’ll need to be running some pretty chunky rubber to get an advantage from them.
30 mm external usually translates to around 24-25 mm internal, which is a bit more ‘normal’ and can be used with most 2.2-2.4″ rubber. The DT EX 471 is 25 mm internal to give you an idea.
I wish all rim brands would just use internal diameters as that’s what decides the tyre profile and it would end all this confusion.