I just put a set of Rebel 18" takeoffs on yesterday. I posted before and after pictures for comparison. Even though I don't do much off-roading, I do a little, and was very uncomfortable with the narrow sidewalls of the 22's. I love having the extra 2" on the 18's. I thought the ride was good with the 22's but do believe it is a little better with the 18's, even though they are LT tires. I plan on replacing them with non-LT tires sometime in the near future (the takeoffs came to me with only about 25% left). After just a short trip, there doesn't seem to be any difference in MPG. The Wrangler tires do have a noticeable road noise hum which is to be expected.
There is less than an inch difference in diameter with the Rebels being slightly larger. The original set up with 285/45 R22 Pirelli Scorpion Verde tires is 83 pounds, the Rebel set up with LT275/70 R18 Goodyear Wranglers is 82 pounds. According to my research, going with a non-LT tire would shave about 10 pounds off of that. Would be interesting to see how that effects ride and MPG. Still debating if I want to do that. I don't do enough off-roading that I need to be too concerned about having an LT tire. I think a non-LT tire would definitely improve the ride (though it's not bad now).
The 18" rims are a very tight fit but there seems to be enough clearance. I can see how others have had trouble with the balancing weights rubbing if they aren't placed toward the outside of the rim. If you are considering going to 18", I guess you need to be careful about aftermarket rims not fitting.
If you're wondering why I originally had 22s (which I didn't want), you can see that story here:
New truck and tires don't match the sticker...?
Now I just have to figure out what tire to go with that will give me a nice (and quiet?) ride but still has some off-road capabilities. Any suggestions?