my thought train....hybrid with 40 plus mpg i could do heavier wheels and lose a few..i was getting 28-30 with the scion with a supercharger ..so as long as i don't get under 35 with the lexus I'm good...Gotcha. Well, let me know. Weight was a factor for me since this is a hybrid AND my daily driver. But I wanted to go as VIP as possible. LOL.
I upgraded my 06 Prius to 205-60-15 BFGs on stock wheels. The tires weighed 5 lbs more per wheel, and I lost nearly 5 mpgs, but it was worth it for improved handling and wet traction. There are always compromises. I'm OK with the stock wheels on the CT. I only wish they weren't chrome. I'm not into bling chromes, and would prefer the stock alloys, or the dark gray available in Australia. I do like the wheels you are considering, just not as 19s.
A 19 will ride much worse, and probably lose a few MPGs, but it looks like you've already thought about that.