I had my 295/70/18 terra grapplers w/ 18" xd hoss rims installed around 2 months ago and love them! Mine is a 4.6 double cab rwd. I drive 70% hiway miles and computer says I am averaging 15.5 miles on a consistent basis. My question is am I actually getting more miles to the gallon than the computer says. I thought I read somewhere that I actually get around 10% more because of less revs on the bigger tires than stock. I have not installed the hypertech module and right now do not plan on it. Any help is appreciated, thx.