Eating crow....2018 Ram Power Wagon build

This is a snapshot of what I see on most road trips/highway travel in the PW when traveling at 70mph (speed GPS and mathematically corrected for tire size to 63mph). I have 37x13.50x17's which are 11.68% larger in diameter than the factory rubber. This equates to a -10.46% speed variance. If you take the 14.3mpg average seen in the pic (it's usually more like 14.7-14.9mpg) and multiply it by .1046 you get an adjusted 15.79mpg's (16.46mpg if you use the 14.9mpg average I see more consistently).
In town I see roughly 11mpg on average, corrected that's actually 12.15mpg, not the best, but no worse than the 4Runner and Land Cruiser on 33's we had a few years back. The range estimate shown is based off of the previous tank where I averaged under 10mpg's due to the majority of my travel being under 15mph off-road at the ranch.

Obviously there are other factors to consider like the increased rotational mass from the heavier wheel/tire combo, increased drag from the larger contact patch, and reduced aerodynamics from the higher vehicle and increased air flow underneath. The lie-o-meter is not always consistent when compared to real world calculations and I have no idea how far off the computer is on these trucks, but I will be sure to hand calculate the next interstate travel tank with the -10.46% variance for comparison. On a recent trip back from the coast I tried setting the cruise to a shown 57mph which is actually 63mph when corrected for the larger tire size. I averaged a shown 15.7mpg's on that 60 mile run which is 17.3mpg's when corrected, a small improvement but 1-2mpg's more for a 5-7mph reduction in speed isn't half bad if I have the time to go slower.

I don't know about y'all, but that is more than acceptable milage in my book for a 7000lb truck on 37's. How does your PW/Cummins compare?

 
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My 2018 is completely stock. I averaged 11.9 towing 4.1K from Florida to California. Best tank of gas has been 16.1 (all highway). Lately I have been in the low 11 MPG range, but I have been off road a fair amount.
 
This is a snapshot of what I see on most road trips/highway travel in the PW when traveling at 70mph (speed GPS and mathematically corrected for tire size to 63mph). I have 37x13.50x17's which are 11.68% larger in diameter than the factory rubber. This equates to a -10.46% speed variance. If you take the 14.3mpg average seen in the pic (it's usually more like 14.7-14.9mpg) and multiply it by .1046 you get an adjusted 15.79mpg's (16.46mpg if you use the 14.9mpg average I see more consistently).
In town I see roughly 11mpg on average, corrected that's actually 12.15mpg, not the best, but no worse than the 4Runner and Land Cruiser on 33's we had a few years back. The range estimate shown is based off of the previous tank where I averaged under 10mpg's due to the majority of my travel being under 15mph off-road at the ranch.

Obviously there are other factors to consider like the increased rotational mass from the heavier wheel/tire combo, increased drag from the larger contact patch, and reduced aerodynamics from the higher vehicle and increased air flow underneath. The lie-o-meter is not always consistent when compared to real world calculations and I have no idea how far off the computer is on these trucks, but I will be sure to hand calculate the next interstate travel tank with the -10.46% variance for comparison. On a recent trip back from the coast I tried setting the cruise to a shown 57mph which is actually 63mph when corrected for the larger tire size. I averaged a shown 15.7mpg's on that 60 mile run which is 17.3mpg's when corrected, a small improvement but 1-2mpg's more for a 5-7mph reduction in speed isn't half bad if I have the time to go slower.

I don't know about y'all, but that is more than acceptable milage in my book for a 7000lb truck on 37's. How does your PW/Cummins compare?

I think your best bet is to use a gps to determine the miles traveled and divide it by the gallons used.

Using the variance method and going off the trip computer may only give you approximate results.


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I used to hand calc the mileage in my PW, until I realized that the computer was giving the same numbers as my math. Only variance was due to tire size change and I can do that in my head.
 
I think your best bet is to use a gps to determine the miles traveled and divide it by the gallons used.

Using the variance method and going off the trip computer may only give you approximate results.


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GPS, hand calculated, and variance are all within .10-.20mpg of one another. I've done the math backwards and forwards and it's all very close, which tells me that the Ram computer is actually very accurate.
 
I think your best bet is to use a gps to determine the miles traveled and divide it by the gallons used.

Using the variance method and going off the trip computer may only give you approximate results.


Sent from my iPhone using Tapatalk
GPS, hand calculated, and variance are all within .10-.20mpg of one another. I've done the math backwards and forwards and it's all very close, which tells me that the Ram computer is actually very accurate.
I’ve found the same with the Ram computer.


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