merge or use mapinstall for cnnorth america 2025.20

Hi all just having a problem with the new maps on garmin. I have a unit that has life time maps but I also have an old 255w which can not handle the big maps now and they are split. when I update my garmin, the map comes split with D9644070a.img and gmapprom.img. Garmin express installs the update fine to the lifetime gps but when I put the old 255w in. it says its not supported. I get it that its outdate but I managed to find an older map 2024.20 that was posted and it was the pc version. I followed the instructions to unzip it and used mapinstall to reduce the map down to the size i needed and added it to the old gamin device.
My question now is, I have a copy of the new 2025 map but its not for the pc version, mapinstall does not see them at all, Is there a way to convert the 2 files so that it becomes the pc version? or is there any other mapinstall (type) program that can take the two maps and let me choose my areas that i need and install it to the older garmin device?

Thank you

freeage wrote:I also have an old 255w which can not handle the big maps

Your nüvi 255W can use an SD card up to 32 GB

freeage wrote:Hi all just having a problem with the new maps on garmin. I have a unit that has life time maps but I also have an old 255w

Your LM device should give you an option when using Garmin Express to install the latest maps to your PC.Then you can use UnLockMapSource this will allow you to make custom map sets that are Unlocked the size you want.