Wheels fly off my car as soon as I run the game

Hi i’m new to unity and have recently just been playing around trying to learn the basics. I’ve managed to follow this tutorial here car controller video up until the part where he assigns the wheel colliders to the script, but for some reason my wheels seem to float in the air when I add the wheel colliders and run the game. I’ve tried to find solutions online, but couldn’t find anything. Does anybody know?