Right now I have a stock 2005 v8 sport t4r with Firestone Destination a/t 265/65/17 tires. I live in Southern CO, I drive on interstate 50 miles 2 times a day and when I go 70 my computer shows 22Mpg and when I calculate seems like im getting 20-21. When I go 80-85 It shows 18-19mpg on computer and I calculate 18-19. These are good dry conditions, low wind, and a generally flat drive. My question is does anyone out there have a lift and some more aggressive tires and still get 19+ mpg on interstate (or highway- when i go 55 on CO HWYs comp shows 22-24 mpgs).