Alright I have a question on fuel milage. I just towed a little 6x10 enclosed trailer abuot 1800 miles and got pretty low mpg, around 11 or 12. I kept the speed around 70 to 75 mph. The trailer had 1 harley in it for half of the trip so there was not that much weight in it going there or back, the milage stayed the same for the whole trip. I put the 315 tires on about the same time it got cold, so the milage fell off alittle more than it has the past couple of winters but I have been getting around 13 mpg just driving around. Last year I got about 16 mpg in the winter months and 19 mpg in the summer. It does not seem to matter how much weight I pull either the milage stays the same. It can be 1000 or 10000 it stays the same. I would think the mpg would get worse with more weight? Any help would be great,Thanks

 

I'm not sure how it works on newer trucks, but have you corrected your speedometer for the taller tires? Having said that, you do have that old gal tuned pretty agressively

 

G1625S has a point,corrected your speedometer? if you did not.I have 4.10 gears so i put 38" tires to get better mpg on hiway,now i can cruse around 70 -75 with my r"sss below 2k.I used a GPS to check my speedometer and am off by 7 or 8 mph at 60. superlift makes a Truespeed recalibrator http://www.superlift.com/accessories/truspeed.asp for about $200 don't have 1 yet but soon.

 

Thanks for the info guys, I was figuring for the speedo being off. I checked it on the highway this weekend and figure its off about 10% or so. It just seems odd, I had this same set up last year in the winter and got around 16 mpg just around town. I was kind of wondering if my timing might have moved or something? The power seems ok. I did not think the tires would make that much difference.