Consider to follow if you like what I do.
Just ask if you have an idea to a lego piece you want to be made.
Lego Porsche Rim for 68.8x36ZR
Its tigher than normal rim to get more grip between rim and tire.
Edit, Feb 22. 2019
Added another version with smaller diameter - named "[...] smaller"
Remember to use at least 6 perimeter lines