If you find a website offering a direct download of a "Retro Rewind ISO" (without requiring a vanilla base game), that website is engaging in piracy. While downloading might be tempting, it violates Reddit rules, Discord server terms, and most forum policies.
First, a few important notes:
It seems you're asking for a of a specific fan-made ISO: Mario Kart Wii Retro Rewind . Mario Kart Wii Retro Rewind Iso