I was thinking the other day, Hankook makes a great HPDE tire (200TW RS-4) and they make other racing tire and slicks like the TD Z214 and faster, and I wondered why they didn't make a tire in the middle to compete with the Nitto NT-01, Maxxis RC-1, Toyo R888R, etc. I did a search and say the Hankook Ventus Z221 which comes in 3 compounds (hard, medium, and soft), and it looks like it slots right in between the R-S4 and the TD Z214.
https://www.hankooktire.com/global/tires-services/competition-cars/hankook-ventus-td-z221.html
However, except for a few very limited sizes on discount tire direct, and some ebay sellers selling some old 2012 stock, it looks like this tire isn't available in the US.
Has anybody ever run them?