I am not sure if this will help but try posting a question on Quora and Reddit. I hope that you find the answer that you need in order to finish this build. I am sure that you will not have a hard time searching for automotive accessories for it. There are plenty of shops to explore such as...
This is really cool, but I'm not sure about painting the brand and model of the tires. By the way, the wheels on it are similar to Vorsteiner because of its 10-spoke design.
I found this on the internet check it out if you're still looking for a reference:
I don't run RG1 on my EK, I am currently using the American Racing wheels AR904 model.
The progress looks good, you surely know what you want for this car considering the purchase list that you have indicated. Good luck, and I am excited to see how this build will turn out.