DirkDJ's assertions are not correct.
As far as IO540 describes a 25kt wind is one that is measured at 30ft (or 10 metres).
Whilst Bookworm mentioned the lower certification criteria the actual value will be the lower of two values - either the highest windspeed at which controllability was not an issue (TPs assume the 'net pilot') or the highest value witnessed (often seeked out) during the certification period.
Some aircraft have a gusting value also.
The Bulldog, for example, has a 35kt limit
but the gear is extremely sensitive to side loading
A very fine reason for crosswind limitations being 'demonstrated' (and therefore somewhat woolly) is that in strong or gusty wind conditions the actual tower wind value may not be terribly close to that of the touchdown zone wind. This is especially true if the tower is using a 10 minute average.
If you plan as if it is a 'hard' value and fly what you feel comfortable with then it is unlikely that you will end up foul of any insurance implications.
cheers
m