Happy Saturday. I have done extensive searching but couldn't find a specific answer. I'm looking to better equip my 07 F250 6.0 with 3.73 gears for better towing. The truck is stock except for an atlas 40 tune, studs, and BPD egr cooler. I use my truck almost exclusively for towing. Either a 10k 5th wheel for camping all over California or a gooseneck rolloff trailer I use for my side business. I have no complaints pulling the RV, but the gooseneck can get pretty heavy. While towing the GN I usually stay within a 30 mile radius from home but there is a lot of stop and go, backing, starting on hills, etc (think local delivery truck). My max speed while towing is 62 mph. I currently have oem lariat 20" wheels with stock size tires but I have some 18" wheels i will install with stock size tires when it's time for new rubber. I've begun saving up for a gear swap but I'm second guessing whether or not that is the best option. If so, what ratio is best with stock size 18" wheels/tires. I'm not as concerned with fuel mileage as I am about reliability and longevity of my truck.

Thanks in advance!

 

I should add that I talked to a reputable 4x4 shop that would do the swap. He said a 4.30 gear would be too low and suggested a 4.10. Some of the research I did said swapping from 3.73 to 4.10 wouldn't make much of a difference. Using some online gear ratio calculators gets me even more confused.

 

The outside circumference of the tire will/should be the same between the 18" rim and wheel combo and the 20" combo as long as they are stock tire size, the main difference in my mind is the 20" tire will have a stiffer sidewall due to it being shorter, the sidewall that is. Here is a link to the discount tire calculator, the difference between the two tires is the 18" combo has 1/2" more circumference or just shy of 3 revolutions per mile so it makes the effective gear ratio slightly higher, but I doubt you would even notice. http://www.discounttire.com/dtcs/infoTireMath.do
I goofed on the numbers, the 18" combo would actually be 3"'s smaller circumference and 16 more revs per mile so effective gear ratio would be slightly lower.

 

Thanks for the link. My main concern is deciding which rear end ratio to go with. I'd hate to go through the trouble and expense of the 4.10 and not really gain anything. On the other hand, I don't want to go too low.

 

4.30 gears are what the "tow boss" duallys came with

 

That's essentially what I'm going for. A "tow boss f250." I don't need the payload capacity of a dually but I do a lot of stop and go towing. I wish Ford would offer more rear end choices from the factory.

Next question. Should I stick with OEM ring and pinon or are there aftermarket sets that compare? I've heard good thing about Yukon. Any pros and cons?

 

Some info on the tow boss and the link is to a thread with some gear ratio discussion that may help a little:

Late in the 2005 model year, Ford came out with a new option for F-350 DRW pickups. It was called the TowBoss pkg. It included a beefed-up rear axle with a 4.30 axle ratio, and that increased the GCWR by 2,500 pounds to 26,000 pounds. But that was a fairly rare option.

Here is an interesting old thread about the tow boss:
To Tow Boss or not to Tow boss that is the question! - Ford Truck Enthusiasts Forums

This is direct from Ford's website.
Maximum Trailer Weight= 18,300#
Gross Combined Weight Rating= 26,000#
Gross Vehicle Weight Rating=13,000#

No Tow Boss Pack.

MTW=15,600#
GCWR=23,500#
GVWR=13,000#

The Towboss Pack. must be ordered with a 6.0 diesel, and auto trans. It is only available in an F-350 DRW config. It includes the trailer brake controller and mirrors. You can order the Tow Command System which is everything except the 4.30 gears. Second set of figures is with 4.10's.

 

That was a good discussion about 4.10 vs 4.30 gears. Thanks.

 

Yes the 4.30 gear is what you want. You will feel a big difference.

 

The only down side is your gas mileage should also go down.

 

^^ I'm not concerned with gas mileage. My truck uses diesel. 😁

Seriously though, I would expect my city mileage to stay about the same or maybe even improve a little. The truck rarely gets used empty on long trips. That's what the wife's car is for.

Any input on gear manufactures? My gut tells me to use OEM but those appear quite a bit more expensive than Yukon or Nitro.

 

I would think towing your mpg could stay the same or better. I'd just tell the guy doing the switch you want know noise coming from the gears he uses. My son went to 4.56 gears but he has 35 tires, and they are quite. Don't know who's gears they installed.

 

The duallys had an effective gearing change compared to SRW from the factory - DRW trucks had 31" and SRW had 33" tires. That's a 6.5% difference.

It's like taking a SRW with 3.73 and changing the gearing to 3.97 (with the same tires).

 

If you want to re gear the truck, don't fear the gear. 4.30s will be fine.

Sent from my Telegraph using IB AutoGroup

 

"Don't fear the gear." Love it! I was leaning toward the 4.30 and now I'm more confident about that. I still need to shop around a little more for the install. The one guy who actually returned my call quoted $3,800 for front and rear using OEM gears, new bearings, etc. That's almost double what I wanted to pay.

Can anybody recommend a good shop around the Ca central coast?