Luke's probably enjoying the 4th with his wife and new daughter.
Or maybe just catching up on some sleep.
According to Kumho's website, the 225/40x18 size weighs 25.4 lbs. Unfortunately, Yokohama does not list tire weights on its website. From previous research, I can tell you that the ES100 in 225/45x17 size runs 24.4 lbs., and for most brands the 17" and 18" 225's are pretty close in weight.
FWIW, the ES100 beats the 712 in every subjective and objective handling comparison in their test on Tire Rack's website, but the 712's are quieter and ride better. If you haven't already read it, here's the test:
http://www.tirerack.com/tires/tests/...e_you_more.jsp
If it's performance you're after and ride and comfort are not as important, you might consider the Kuhmo MX if you can afford them.
Hope this helps.
Gary
p.s. Steppin Razor - the only weights I've ever seen on the Tire Rack site are maximum load capacities. If there is some hidden feature to click on that gives tire weights, let us know.