WinRAR 5.0 has introduced a new compression format RAR 5.0 and WinRAR 5.50 version released by RARLabs now uses the new format by default. For you to identify an archive on your computer is of what format, right click on any archive created with WinRAR and choose properties and click on Archive tab.
To be clear, the new compressed archives created with WinRAR 5.5 will use RAR 5.0 archive format by default, if you want WinRAR to use RAR 4.x as default compression format like before, you can, here is how.
Make WinRAR to use RAR 4.x format by default instead of RAR 5.0
- Launch WinRAR
- Click Options > Settings,
- Click on ‘Compression’ tab, click on ‘Create Default’ and select ‘RAR4’, click OK to apply the changes.