size of varchar

Hi,

I'm migrating an Access application to use PG as backend.
In the access-mdb I have every varchar set to use max. 255 chars because
on the one hand Access can't have bigger varchars and on the other hand
Access won't need more room for 10 chars in a varchar(255) than in a
varchar(10).
Therefore I have never figured out the really necessary size for
zip-codes, names, phone numbers and what not.

Can I stay with size 255 in PG without getting a space- or speed-penalty ?
I'll use ODBC. Is the size 255 relevant in network transfers ?


regards
A.