Axle Ratio, new truck

Reading the gas mileage reports people are posting online, I think driving style has more affect than gear ratio.

Also with the 10spd I don’t think gas mileage around town would be affected. Only when you get on the interstate in 10th would it make any difference.

rhagfo wrote:
Well tow rating with 3.73’s is 17,000#, with 4.30’s (4.10’s not an option) about 19,000 to 20,000#.
I think I would want 4.30’s.

Since the OP said, he's buying a 15,000# trailer, either are well within tow ratings.

With the 10 speed transmission and being well within ratings, the axle ratio isn't critical for towing. This is different from the old days of 3 & 4 speed transmissions where if you couldn't hold top gear, your RPM went thru the roof if you had to downshift and that ate into MPG. With 10 speeds to choose from, the truck will pick the gear that results in the best engine RPM while towing regardless of axle ratio because it has enough gears to find one that provides that RPM.

When running empty, you will likely get a boost in MPG. One thing to be careful of with big trucks is 1 MPG going from 12 to 13 MPG is an 8% improvement. Improving a 50 MPG car by 3 MPG is only a 6% improvement. Small numerical changes in low MPG vehicles make a much bigger difference.

Now if the OP wants to exceed 17,000#, that is when jumping to the 4.30 starts making sense.

Since you are buying a DRW gas engine tow vehicle, you will want the most towing capacity, which means the 4.30 ratio. Having 4K more tow capacity is a huge benefit to a gas DRW TV! Even using it for everyday use, you likely won't be able to measure the mpg difference, with 10 speed. If towing the mpg may be better with the lower gearing, but certainly not worse.

In any case, it will be a big capable truck! I'd be more concerned with reliability, and how it rides, rather than mpg.

Jerry

How much does your GCVWR impact your tax and registration costs? With a 10 speed trans the old opinions regarding axle ratios no longer apply.

Unless your crawling up mountains all the time stay with the 3:73's.

blaczero wrote:

rhagfo wrote:
Well tow rating with 3.73’s is 17,000#, with 4.30’s (4.10’s not an option) about 19,000 to 20,000#.
I think I would want 4.30’s.

Right, 4.3 not 4.1 thanks. Ya just looked at the book again, goes from 16k with the 3.73 and 20k towing with the 4.3.

How much of a gas mileage hit is it to go to 4.3? We talking 1mpg? or like 5?

Well we went from a Ford 460 to Dodge CTD and doubled my mileage!
1988 F250 460 with C6 auto, to a 2001 Dodge Ram 2500 CTD 5.9 with 5 speed and 3.55’s went from 7 mpg to 14 mpg in town.
Current Ram 2016 3500 DRW Aisin, 3.73’s about 12 around town. Tow capacity 25,024# doubt I will ever drive a gasser again.

rhagfo wrote:
Well tow rating with 3.73’s is 17,000#, with 4.30’s (4.10’s not an option) about 19,000 to 20,000#.
I think I would want 4.30’s.

Right, 4.3 not 4.1 thanks. Ya just looked at the book again, goes from 16k with the 3.73 and 20k towing with the 4.3.

How much of a gas mileage hit is it to go to 4.3? We talking 1mpg? or like 5?

Well tow rating with 3.73’s is 17,000#, with 4.30’s (4.10’s not an option) about 19,000 to 20,000#.
I think I would want 4.30’s.

Slightly better MPG with the 3:73
Better towing with the 4:10

With that 10 speed tranny....go 3:73

3.73 would be fine particularly for a daily driver IMO. However you don’t indicate a home location or where you travel.