I believe you are right on them requiring the 19s. My gt came factory with 19s and I ordered a new set of 19x11s for sticky tires. I figured it was not much more for the 6pots. Might look into a track day to test them out this year but I'm trying to get about 20 AX events in this season.These look tasty. Will 18” clear the 6 pistons? I was under the impression 19s were required. It’s a big reason I went with 4 pistons.