ok guys im starting a new thread here to get as many opinions and experiences i can
heres the deal:
i drive a 2006 F250 crew cab lariat 4x4 6.0 Powerstroke.....im currently running stock gears which are 3.73's.... im wanting to upgrade tires to 37x12.5x17... it is a daily driver... very light towing if any
WHAT SIZE GEARS SHOULD I GO TO FOR BEST OVERALL (MPG's, AND POWER) PERFORMANCE?

 

I think your best bet is a 4.56 how ever the others are real close. But some friends of mine like the results of the 4.56

Staying with the 3.73 would not be too bad if you went with a little smaller tires. But with 37s I suggest the 4.56
Yukon Ring & Pinion Gear Set for Ford 10.25" in a 4.56 Ratio

 

Power and MPG's are on opposite ends of the rear end question. I'll disagree with Rock on this one. If you've got a good tune, there's nothing wrong with 3.73 for a daily driver and light towing. My wife has 35 x 12 x 17 tires and her old fashioned 7.3 does just fine with 3.73's in it. You might consider 4.10 if it seems too slow off the line, but your mpg's will suffer. Unless your RPM's are too low while cruising around, I'd leave the gears alone.

 

Chris is wrong once again. 35's work good on 3.73 not with 37's put some 37's on there Chrris then talk. about MPG or do the measure trick with the tire roll and the DR shaft to figure it out. MPG go way south

 

I was just poking Chris- he likes to do that to people for some reason. So I was kicking him back

Most people put on 37 for more than road so if your off roadin much I suggest the 4.56 over the 3.73 for the start stop gain you get with the turn over. But if your hwy trucking I would run smaller tires and keep the 3.73

Here are a few stats to make you think--

MPH: 70
Gear Ratio: 3.73
Tire Diameter: 37

Your RPM is about
Automatic Without Overdrive 2,505
Automatic With Overdrive 1,660
Manual 2,371
5 Speed 1,897
^^^^^^^^^^^^^^^^
MPH: 70
Gear Ratio: 4.56
Tire Diameter: 37
Your RPM is about
Automatic Without Overdrive 3,067 whoa
Automatic With Overdrive 2,029
Manual 2,899
5 Speed 2,319

at 50-------------------
Gear Ratio: 3.73
Tire Diameter: 37
Your RPM is about
Automatic Without Overdrive 1,789
Automatic With Overdrive 1,186
Manual 1,694
5 Speed 1,355
---------------------
MPH: 50
Gear Ratio: 4.56
Tire Diameter: 37
Your RPM is about
Automatic Without Overdrive 2,188
Automatic With Overdrive 1,449
Manual 2,070
5 Speed 1,656

_______at 35 mph
MPH: 35
Gear Ratio: 3.73
Tire Diameter: 37
Your RPM is about
Automatic Without Overdrive 1,253
Automatic With Overdrive 830
Manual 1,186
5 Speed 948
------------------
MPH: 35
Gear Ratio: 4.56
Tire Diameter: 37
Your RPM is about
Automatic Without Overdrive 1,531
Automatic With Overdrive 1,015
Manual 1,449
5 Speed 1,159


So as you see the difference for hwy is about 150-300 to 500 or so.
Now starting and stoping is where the 4.56 is better. But why not just go with 35's and keep the 3.73 and tune it. But if you have to go with 37's and stop and start alot and off road a lot then go with the 4.56

Personally I use to switch mine out for deer season just for those reasons. Tires that is. I run a 410.

 

rock ur funny. lol. how come no one wans to poke me? lmao!

4.10 is gonna hurt the mpg somewhat. i cant remember if mine was a 3.73 or 4.10. she has a little giddy up and go. lol.

 

maybe this is why

 

what about 4.10's with 37's?? wouldnt that be in the middle of 3.73's and 4.56's?? how would that affect me?

 

I love the 410 on the 7.3 for off the line response. If you vist rock crawlers or off roaders you see more of them speaking favorable about the 456 than the 373 or the 410. I tow heavy so 410 is good for me. However If your more into the look of big tires verses the down in the mud or rocks then 410 should work fine. I can run numbers on that but its mostly in the middle of the others I listed.


Edit
You can get retuned after the mod too

 

right i just notices that you were talking about 3.73's which is what i have now and 4.56's which with the research ive done i think are just gonna be to much for what im looking for... i was thinking more about the 4.10s or 4.30s???? but i was kinda just looking for info on if these would be better then my 3.73's (which they should compensate for the 37's)... pretty much im running factory gears and factory tires right now which is a good set up i like the balanced performance BUT since im going up to 37's i know i need to go up in gear in order to match performance wise.... i wanna stay close to my stock performance but like i said bigger tires means i need the gears to match... is that confusing??

 

rock, tats funny right there. now u folks, if y'all dont tink tat was funny, y'all gotta leave now, u hear? lmao.

btw rock, is tat slow-poke rodriguez? cos tat dont look like speedy.

 

You know your toons

Tats y you are not being poked.

 

hahahaha.

to the OP, yeh 4.10 is more of the mid-range kinda performance. still, at the end of the day, it's up to u.

 

Shush you. She's already talking about wanting bigger tires.

Just for clarification, I understand the auto options, but are you saying manual and 5 speed numbers are both the standard transmission numbers? If so, are you talking ZF5 or ZF6 (I know, final drive ratio is about the same on both).

But if you look at the new diesesl, they're selling them with 3.31 rears due to the higher hp, which is why I mentioned the chip. Besides, we're not talking about rock crawlers or serious off roading. He originally asked about


I don't know. It just seems to me that if you can get away with less than 300 hp on 35's with a 3.73 rear, then you should be fine if you bump it up to around 300 or more and run 37's and a 3.73. I guess it all would have to do with your driving style and terrain.

 

My close friend runs the 37 on his and has the 6.0 2003 and the 373
He does well on fuel. But here it the difference. He runs 130 hwy miles daily, very little around town. Lives in a small town. He also never off roads. Nor tows. So it really is not just driving style its life style. We are going in the motor in march on his and do a few upgrades. He wants the 410 even though I dont think he needs it because of his driving and life style. But he said he wants better off road performance. Well he only takes it off road once in a blue moon, but with the hp upgrades he wants the 410 so thats what we are doing. Just got finished talking to him this morning about this thread and thats what he wants. Chris the numbers are generic and are a captured guestamate (close but a calculated guess) so they generically apply. The error range it about 175 +/- too many other factors to consider to make the formula be more precise than it is. However I like to piddle with the excel calcs and formulas so I could make it have more detail it is just not that advantagous to add the other transimision ratio factors.