What brand and size are the first set you added? How much bigger are the second? Have you noticed a difference in ride and mpg between them? Any lift/level?
The first set of tires were BFG KO2s in 275/65r20. Basically a 11" wide by 34" tall tire. Gas mileage was pretty close to the same as stock once I corrected the speedometer.
The second set of tires that I am currently running now are Atturo Trail Blade XT. They are a hybrid AT/MT tire. Size 305/55r20. These are 12.5" wide by 33.5" tall. Gas mileage again is about the same. On the highway I am averaging about 18 mpg, but that is running 80 mph. If I baby it I can get over 20. I have been impressed with the Atturo tires. I went with them because my wife was ready to kill me buying new wheels and tires for a second time. Figured I would try them out and save a little bit of money, especially since I am considering a 6" lift and will be switching to 35s when I do. That will be sometime next year if I do it. They perform well and ride pretty good, just a little noisy. I usually have my radio up anyway though so it doesn't bother me between that and my Carven exhaust.
The ride is still pretty good. A little stiffer just from going to a 10 ply tire, but still smoother than my 4th gen.