Modern USB Loaders (USB Loader GX, CFG Loader) now support (e.g., RMCE01.wbf1 , .wbf2 ) for FAT32 drives. Since FAT32 cannot handle files larger than 4GB, and Mario Kart Wii is under 4GB, you typically won't need splitting.
Before diving into tutorials, you need to understand the acronym. stands for Wii Backup File System . It is a file system developed by the Wii homebrew community to store Wii game backups on USB drives. mario kart wii wbfs