Tire tread and fuel mileage

[Toad]

I purchased a 2014 Ram 3500 this summer. It had 35 12.50 18 BFG AT on it. I just replaced them with Toyo AT2 in the same size. The Toyo has a slightly more aggressive tread pattern than the BF that I just replaced. Today I pulled a Jeep down to Alpine. Fuel mileage was awful. The readout was 10.8 mpg. Prior to the tire change the truck would typically average 12.5-13 pulling similar weight. Tire weight between the two tires is equal(within a couple pounds). I have a hard time seeing that much of a performance drop just from a slightly more aggressive tread. Truck does seem to downshift more from 6th to 5th gear also.

 

[Homefryy]

The new tires may have a larger diameter than the old ones either due to the old ones being worn or just the Toyos being larger. Most tires aren't true to size so one model tire that is a "35" may actually be 35" diameter but another model "35" may only be 33.5" in diameter or something like that. If your new tires are actually larger than the old ones your truck won't think it is traveling as far as it actually is so the computer will report worse mileage than what you are actually getting. The tires being larger would also explain more downshifting.

 

[SLC97SR5]

I believe the Toyo's are a bit heavier right out of the mold.
68 lbs vs. 67.59 lbs.

I am running the AT2's and KO2's in the same size on different vehicles and the Toyo's seem to have a bit more beef to them.

I don't really track mileage on my F350 but I noticed a definite decrease in fuel range and even increased cruising EGT's after switching from Toyo HT's to the AT2's.

 

[SLC97SR5]

Another thought...is this your first time towing on winterized diesel in this truck?

 

[Toad]

I actually had that thought after I posted this. I think I have had winter blend fuel in it before this week. I think I am going to get a few more miles on it and see what it does. I have thought about dropping a size in tire. See about possibly finding a tire that is slightly less aggressive. Anyone had experience with Nitto Terra Grapplers? I know it is the same manufacture essentially. It just has a tighter tread pattern.