Yes and no. Yes a taller tire is the only way to bring the lowest parts of the truck higher off the ground. So your rear diff, LCAs, drive shaft, abs sensors, etc. But a lift will also increase your approach and departure angles allowing you to go over larger obstacles and it will raise a lot of...
I did a 3" lift in the front, 1.5" in the rear, went to a 285/75r18 (35x11.8) and my mpgs were virtually unchanged. Little less power/torque, but I notice that mostly towing the boat up hills. My truck takes a little longer to get to 5th and 6th gear. But again, my fuel cost over a year without...
Lots of variables there. If you lift 2.5"+ and you go with a shock that doesn't have a reservoir, you can go all the way up to 285/75r18 or even 295s without rubbing and without having to do a BMC. There's some caveats there though. If you go 2.5"+ in lift height and stick with the factory...