I found that I have to use a class(4) SDHC card. I use an 8 GB SDHC card in both my 255W and 660. At first I had bought a higher speed card, and it was not recognized. Thanks to BestBuy for pointing that out to me.
When reading my Garmin faq, it says other limitations may prevent full use of the SD card meaning a 32 GB card will work but you will only be able to use 4 GB of it because your units has a limit of how many maptile, photos, waypoints, etc it will store or retrieve. They suggest a 4 gb card for my gpsmap62 and the 78 series.
Just got off the phone with Garmin tech for help upgrading my map. They said any 4 or 8 GB SD card will work in my Nuvi 265W. The current map size is over 2GBs and it needs space to do the install. That's why I could not uprade my map. The device came with 2 GB internal memory.
First off; I'm completely new to Garmin and car-GPS in general.
I have just downloaded the free map update from Garmin: When I'm about to install it, the software tells me that there are too little space on the GPS, thus I have to choose which parts of Europe I want installed. However, I have installed a SDHC 8gb in the GPS, so I don't see why it would be too little space.
As a side-note I can say that the Garmin web application doesn't seem to discover the SDHC card; according to the web application, there are only 15mb unused space on the GPS.
What should I do?
I found that the solution to my problem was to create the folders on the SDHC card, similar to the folder-structure on the GPS (ie. Garmin-->POI etc).
I have tried my 8GB SanDisk Ultra SDHC 15mb/s card from factory default on my Garmin Nuvi 265W and didn't work. I then updated my firmware and found that the card worked. It could be possible that others experiencing SD card issues may need a firmware update.