I have a 2013 cm with 40k miles. I pulled my icons co and 20"wheels and 35" tires off my old 07 tundra and swapped the the 13. So lift wheels and tires are not new. Any way. I was getting the normal 10-11 mpg's and did not think much of it. One day while driving my normal style mpg's tanked to 6-7. Though it was a fluke. Next tank while watching my driving style close got the same 6-7. My air filter was bad off so I changed it and made sure the air in my tires were good (they were) Still next tank 6-7 mpg's. I went to work the next day at the FD for a 24hr shift and disconnected my battery to reset the ecu. Left it unhooked for the full 24hr shift. Next day hooked it up and filled up the tank. Got 12-13 mpg's for the next two tanks!! More than ever with my lift and tire combo! That shocked me. Well I'm going on two long road trips over the next 3 weeks. 5hr and 10hr one way. Most all interstate so I decided to throw my old oem wheels (18 alloy)and tires on just for the road trip. Yes the truck looks dumb with the lift and oem tires but it's just for the road trips. Just got back from the first one and got 16.7 mpg's!!! Never thought the tires would suck up 5mpg! So guessing I will be doing some math on lighter weight wheel tire combo's while trying to stick around 34"-35". Was already planing on doing 4.88 gears. But with 5mpg difference it would not take to long to justify a different tire wheels setup. I drive around 18-20k miles a year. Any advice on different wheel tire combo would be welcome. I was just rattling off hear bc my wife could give two shits about my truck addictions Hahahah. Thanks for letting me vent guys!