Disclaimer, this is in no way intended for driving actual karts. This is just meant as a decoration. 

This is designed to be used along with Matt Amys' video (but you can scale it according to your kart tyre dimensions if you are following along with the video): 

This model is from the 2019 Renault F1 car rear rim. It has been elongated to make it fit into the kart tyre that I had. I printed it on my Prusa Mini+ in 2 pieces due to the height limit.