Hi All,
I know 'information is power' but here are typical speed ranges for the -300 and -500. I have no info on the -600.
A340-300 at MTOW is 280kts whilst at 40 tonnes less it's 256kts. For A340-500 it's 269kts and 253kts respectively.
REF QRH 4.01. (Please allow for rough interpolation
)
Hope this helps,
Happy Flying