Lemf
Download Mapsource from GARMIN website and install on computer.
Download latest map data torrent from
[Please Register or Login to download file] . I´ve used it and it works.
Unzip the contents and work your way thro´ the folders till you find
CNEUNT2013_10Update.
Click on this file and it will install the info into MAPSOURCE.
Using Mapsource you can create mapsets that will fit into your GPS memory.
There are excellent tutorials to assist you in updating the necessary files of your GPS.
Remember to backup your files before modifying.
I have a Nuvi255W so I assume they are similar.
Any probs then come back to the forum.