Rob, do you have the tornado fuel saver? :sombrero:
No. In fact, I heckle those idiots whenever I encounter them at trade shows.
I don't quite understand how you can claim to normally get 18+ mpg in a lifted disco with large tires when your truck was only rated at 12mpg from the factory. Getting 15+ with your marriott on wheels is just ridiculous.
Wow.
First, the factory rating is
12 City, 18 Highway. The milage I'm reporting is highway milage. Second, go back and read what I wrote, as I said I got a best of 18.5
when stock.
Lastly, my tires are only 8% taller than stock, so not very big, and directionally larger diameter makes the effective gearing more favorable anyway. They are also 245's, vs. stock 255's. And they're LT-E's running 45psi vs. 35psi stock so less rolling resistance. Lifting a high clearance truck doesn't affect milage as much as you'd think, because you aren't actually increasing the frontal area that much, since much of the air just goes under the truck anyway.
At the end of the day after all the pluses and minuses, with my mods I only lost a small amount of milage compared to stock. And then towing a heavy trailer doesn't take too many MPG's compared to the surprisingly big effect of putting monkey bars on your roof.