If you are a modern emulator user, is the definitive answer. It gives you the best of both worlds: massive storage savings and lossless accuracy, supported natively by the latest Dolphin builds.
The problem? Most Wii games do not actually use all 4.37 GB of data. For example, Animal Crossing: City Folk only contains about 400 MB of actual game data, yet its raw ISO file still takes up 4.37 GB on your hard drive. The remaining 4 GB is entirely "dummy data"—useless garbage data padded by Nintendo to fill out the physical disc and ensure optimal reading speeds on the console's original optical drive. nintendo wii roms highly compressed
However, from websites—even "highly compressed" ones—is generally considered copyright infringement and illegal in most jurisdictions if you do not own the original game. Sites offering 700+ Wii ROMs for free are usually operating outside the law. If you are a modern emulator user, is the definitive answer
The most trusted tool for this is Wii Backup Manager (for Windows). Most Wii games do not actually use all 4