I also dropped alot too.With stock tire size I was getting 12 mpg in the city,now with 265/70/17 general grabbers at2 ,i am getting a sickening 9.5.I understand I went from a 29.5" tire to a 32 inch tire.How much can that difference in tire size throw off the computer?I am getting my average mpg off the comp and have the hemi.my new tires are 50lbs a piece,this might not help.
You spedo will be about 7.3 miles faster with the 31.7" tire. Your revolutions per mile will be about 46 greater. You bet this will throw off the computer!
2008 Jeep Green Rocky Mountain 4x4 4.7L, 245/65 R17 Fortera's,
class IV tow package w/shackle, front tow hooks, remote start,
MyGig w/backup cam, bun warmers, commandview, QTII,
Rocky Road Super Sliders (now installed and tested!), no lift, full Jeep OEM skid plates,
4xGuard Belly Guard, 4xGuard front skid, Surco 50 x 70 roof rack.