Axle Ratio, new truck
Hey all, I think I know the answer but just wanted to make sure. I am looking into a 5th wheel ~15k GVWR and am buying a truck. I want an f350 and may order a new one to get exactly what I want (there...
Forum Discussion
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.
