Differences b/w available axles
Cargo Master
Joined: Jan 2015
Posts: 2,824
Likes: 39
From: Boise
In all of my truck experience yes. I think the biggest upside is the towing experience. The 4.30 allow the motor to not work as hard and you find yourself not using 2nd gear as much towing 8k. I have 3.73 with 33" tires and my full fill up tank mpg avg is usually right at 10. And I try for decent mpg. I only see my mpg improving for my driving routine.
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New User
Joined: Apr 2016
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Elder User
Joined: Apr 2016
Posts: 633
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From: So. Utah
Dale...... I ordered a '16 F350 dually that has the "high capacity trailer tow" wich is basically an F450 front axle. This option comes with the 4.30 gears so I'm installing 20x7.5" eagle wheels and Michelin 275-65-20 tires, same size as you're getting. There's a big drop in rpms when you go with the 34" tire and the 4.30, here's some examples.
4.30 gears .... 65 mph = 1845 rpm .... 70 mph = 1987 rpm ... 75 mph = 2130 rpm 80 mph = 2271 rpm. So it's realy not that bad when you have the double overdrive trans. Around town it will be much easier to drive I would think, Mine is supposed to be in on May 9th. Oh man, just saw you are getting the gas engine, I don't think it should make that much difference anyway.........good luck.
4.30 gears .... 65 mph = 1845 rpm .... 70 mph = 1987 rpm ... 75 mph = 2130 rpm 80 mph = 2271 rpm. So it's realy not that bad when you have the double overdrive trans. Around town it will be much easier to drive I would think, Mine is supposed to be in on May 9th. Oh man, just saw you are getting the gas engine, I don't think it should make that much difference anyway.........good luck.
Cargo Master
Joined: May 2007
Posts: 3,336
Likes: 4
From: Western New York
Among the reasons for a higher axle ratio is to put less strain on the input side of the differential and to keep the engine and transmission running at a higher rpm. The ratio is calculated between the driveshaft RPM over the axle RPM. If you are planning on off road situations, mountain and hilly operation, heavy foot on the throttle you would consider the higher ratio. But with the engine spinning faster you can expect greater fuel usage, especially if you travel at higher speeds on the open road. And not to contradict you cyncwby, the difference in aspect ratio on the standard 18" tires at aspect 65 to the standard 20" tires at 60 (which are the tires on the SRW) makes both these tires 33" diameter. The 3.73 or even the 3.54 would be adequate, in my opinion. The higher rpm's really love the gas station. And if you really need to pull, low range will almost turn the hubs out of the wheels.
Edit: I am finding conflicting data on the 20" wheels with some listed at aspect 70 and AT tread pattern. These would be taller.
Edit: I am finding conflicting data on the 20" wheels with some listed at aspect 70 and AT tread pattern. These would be taller.
Cargo Master
Joined: Jan 2015
Posts: 2,824
Likes: 39
From: Boise
Factory size is 275/65/20 and are 34.2" tall on average. 245/75/17 are stock too at 31.5" tall. This tire height difference almost nullifies going to a 4.30. I use a lot of fuel having to drop to 2nd when I tow.
Hotshot
Joined: Apr 2013
Posts: 10,118
Likes: 650
From: NH
This is really simple: 4.30 gears will net overall worse mpg, but better acceleration and easier towing. The 3.73 gears are fine in most cases and are generally more common.
The e locker is driver selectable and not automatic. When it is off, there is no limited slip. I think it is a great option but rarely used on a 4x4. It does not engage and disengage quickly. For the low cost, I would get it. Aftermarket cost would be close to $1500 or more for something like an ARB.
I've owned two 6.2 trucks with 3.73 gears. I've ordered a '17 with a long bed crew cab and this time got the 4.30 gears. I'm planning on mpg being worse, but I'm coming from a diesel and need to occasionally tow some very heavy loads. Believe the 4.30 gears allow the towing rating to be higher as well.
The e locker is driver selectable and not automatic. When it is off, there is no limited slip. I think it is a great option but rarely used on a 4x4. It does not engage and disengage quickly. For the low cost, I would get it. Aftermarket cost would be close to $1500 or more for something like an ARB.
I've owned two 6.2 trucks with 3.73 gears. I've ordered a '17 with a long bed crew cab and this time got the 4.30 gears. I'm planning on mpg being worse, but I'm coming from a diesel and need to occasionally tow some very heavy loads. Believe the 4.30 gears allow the towing rating to be higher as well.
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Senior User
Joined: Jan 2016
Posts: 236
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From: El Cajon, Ca
I ordered my 16 with the 4:30 based on the following information that I gathered after hours of research on this site and others.
#1 I plan to upgrade the stock tires from 32.07 dia to 34.26 dia. This would have dropped my gear ration from 3:73 to about 3:55.
#2 I tow in the mountains of the West a lot which at higher altitudes hurts the 6.2.
#3 I might upgrade to a bigger trailer in the future.
#4 I don't use this truck as a DD so the small lose in MPG is of no concern.
#5 After test driving the 6.2 with 3:73 I was a little under impressed with the acceleration of the truck and thought the 4:30 would make that go away. There was no possibility of going with the Powerstroke.
#6 I wanted the tranny to not downshift as often. This might be subjective, but the 4:30 will only help.
#7 Towing was the primary reason for buying the truck.
As other have pointed out to make the change to the 4:30 after the fact is just to expensive. Better to get it that way and then you would never know the difference.
#1 I plan to upgrade the stock tires from 32.07 dia to 34.26 dia. This would have dropped my gear ration from 3:73 to about 3:55.
#2 I tow in the mountains of the West a lot which at higher altitudes hurts the 6.2.
#3 I might upgrade to a bigger trailer in the future.
#4 I don't use this truck as a DD so the small lose in MPG is of no concern.
#5 After test driving the 6.2 with 3:73 I was a little under impressed with the acceleration of the truck and thought the 4:30 would make that go away. There was no possibility of going with the Powerstroke.
#6 I wanted the tranny to not downshift as often. This might be subjective, but the 4:30 will only help.
#7 Towing was the primary reason for buying the truck.
As other have pointed out to make the change to the 4:30 after the fact is just to expensive. Better to get it that way and then you would never know the difference.
Cargo Master
Joined: Jan 2015
Posts: 2,824
Likes: 39
From: Boise
I ordered my 16 with the 4:30 based on the following information that I gathered after hours of research on this site and others.
#1 I plan to upgrade the stock tires from 32.07 dia to 34.26 dia. This would have dropped my gear ration from 3:73 to about 3:55.
#2 I tow in the mountains of the West a lot which at higher altitudes hurts the 6.2.
#3 I might upgrade to a bigger trailer in the future.
#4 I don't use this truck as a DD so the small lose in MPG is of no concern.
#5 After test driving the 6.2 with 3:73 I was a little under impressed with the acceleration of the truck and thought the 4:30 would make that go away. There was no possibility of going with the Powerstroke.
#6 I wanted the tranny to not downshift as often. This might be subjective, but the 4:30 will only help.
#7 Towing was the primary reason for buying the truck.
As other have pointed out to make the change to the 4:30 after the fact is just to expensive. Better to get it that way and then you would never know the difference.
#1 I plan to upgrade the stock tires from 32.07 dia to 34.26 dia. This would have dropped my gear ration from 3:73 to about 3:55.
#2 I tow in the mountains of the West a lot which at higher altitudes hurts the 6.2.
#3 I might upgrade to a bigger trailer in the future.
#4 I don't use this truck as a DD so the small lose in MPG is of no concern.
#5 After test driving the 6.2 with 3:73 I was a little under impressed with the acceleration of the truck and thought the 4:30 would make that go away. There was no possibility of going with the Powerstroke.
#6 I wanted the tranny to not downshift as often. This might be subjective, but the 4:30 will only help.
#7 Towing was the primary reason for buying the truck.
As other have pointed out to make the change to the 4:30 after the fact is just to expensive. Better to get it that way and then you would never know the difference.
I can only add that in all my truck experience, a gas motor that runs somewhat large tires and/or tows gets better(definitely not worse) mpg's when lower gears are used.
Cargo Master
Joined: Jan 2015
Posts: 2,824
Likes: 39
From: Boise
No not the front, just the rear. That would be sweet though. I can remember an old Gen1 Cummins with factory front and rear lockers pulling out a stuck truck on the dunes once. He was the only one to succeed after many other failed attempts by other trucks. Ever since, that image of all four wheels giving full power is engraved in my mind.
Elder User
Joined: Apr 2016
Posts: 633
Likes: 2
From: So. Utah
Rasalas ..... no problem on contradicting me but me thinks something is amiss. The rpm calculations I got off the enet are correct, the Michelin Defender 275-65-20 are in fact 34.1" in diameter. It doesn't matter what the aspect ratio is the calc's go by diameter of the tire.
Not a math major but I find it kind of facinating that the rpm difference between a 3.73 and 4.30 with the same diameter tire gets higher as the speed increases. At 60 mph the rpm diff. is 226, at 65 = 244, at 70 = 263, at 75 = 283 and at 80 it's 301.
Not a math major but I find it kind of facinating that the rpm difference between a 3.73 and 4.30 with the same diameter tire gets higher as the speed increases. At 60 mph the rpm diff. is 226, at 65 = 244, at 70 = 263, at 75 = 283 and at 80 it's 301.