I ordered the tire from Amazon. (Federal SS595 Performance Radial Tire - 255/40ZR18 99W) $102.72, no shipping and no tax. $25 to have the tire mounted. No balancing necessary.
It took a bit of grunt and silicon spray to stuff the tire onto the bike.
Initiating turns or curves takes a little extra effort to lean or extra countersteer pressure on the bar, but after 40 miles it's hardly noticeable. The biggest problem is road irregularities that run parallel with the direction of travel, like sunken pavement due to heavy vehicles.
I've been running on the Darkside since 2006. But this is the first for me on the Nine.