I know this has been beaten to death, but I have to be missing something. 1998 Chev ¾ ton, 6.5L turbo, 4L80E, 4x4, 4.10 gears, 4 inch exhaust straight, number 5 chip, 33x12.5x16.5, 140,000 miles, otherwise stock. I want (like everybody else) better mpg’s. I currently am getting 15 mpg at 55-60. 3 years ago I had the tranny rebuilt, at the same time I did all the oil seals and gaskets and such. I changed the timing chain and gears, not factory set but, equal quality. Before that I was getting 16-18 mpg’s, possible that the cam is outa time? Was told by the local diesel shop that if my marks lined up the computer took care of the rest. I read elsewhere that the timing set with the idler gears was better, true? Could that be my loss? I also had my old 9.00x16’s on there too, tall skinny, wish they still made them. Or is it that the diesel fuel now is just that bad leading to the increase? Lastly I read on cheating the boost sensor with a resistor so it doesn’t add more fuel with the boost, good idea, or snake oil.
Thanks again!

 

Big tires kill the fuel milage on these truck had 285-75-16s on15ish mpg went to a 265-75-16got 18ish mpg and I had automatic with4.10 gears #9 resistor and that was with the air on and windows up running 55-60ishmph my 1993 has 265/75/16s all terains and i get18.5 easy with air on and windows up but thats running 55ish highway milage plummets to 15ish trying to run 70 with a NV4500 not sure the gear but 2800rpm at 70 these trucks came with 245/75/16 I dont know if stock size would get even better mpg???but I kinda think it looks to small for my taste

 

Have had these on both the 93 and the 94 if you can get them balanced right ride real sweet and they are a Load range E tire wild country radial atx

 

Ok cool. I do need new tires, and was thinking of some E or F rated tires. Keep them stiff to have low rolling resist. Would like to get something smoother like those wild country atx. They look grippy enough for running in the woods for firewood.
Was just looking at Multi Miles Trailcutter in a LT255/85R16, tall skinny, close to my old 9.00-16..