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I have a 2005 6.0L crew cab short bed and I recently added larger rims and tires. The truck got real sluggish and my MPG is at 10. I'm assuming the fix will need to come via gears, if the stock gears on my truck are 3.73's my guess would be to add 4.10's for the new set up.

The new tires I'm running are 325/60/18, are 4.10's the right choice?:dunno:
 

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I'm running 4.30s and love em. You down in sd? If your near Anaheim you can try my truck with the 4.30s

And I believe the 325.60 is like a 36in tire I have two n my garage.
 

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I've wondered how 4.30's would do with a 35/36 inch tire. I have pondered the idea of putting them in my truck to get some mileage back. I didn't know if it would hurt or help mpg, I know it'd be a lot stronger down low.
 

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I'm running 4.30s and love em. You down in sd? If your near Anaheim you can try my truck with the 4.30s

And I believe the 325.60 is like a 36in tire I have two n my garage.
The 325/60/R18 is a 33" tire and is about 13" wide. You are probably thinking about the 326/65/R18, which is roughly a 35x12.5 tire. I used to run the 325/60's and have switched to the 305/55/R20 which is roughly the same dimensions but a touch more narrow (33x12). I'm also running 3.73 gears, but the cost to change them out is roughly $1k in new gears for front and rear and the master install kits, PLUS another $1k in labor to have them installed.

Since I tow, I am considering going to the 4.30's to help regain some of my mileage as well as gain some mechanical advantage pulling some of the steep grades with my toy hauler. Otherwise, I would be going the route with the 4.10's...

PS. It's going to take some serious fuel mileage increases to get your return on a $2k investment...
 

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I have a 2005 6.0L crew cab short bed and I recently added larger rims and tires. The truck got real sluggish and my MPG is at 10. I'm assuming the fix will need to come via gears, if the stock gears on my truck are 3.73's my guess would be to add 4.10's for the new set up.

The new tires I'm running are 325/60/18, are 4.10's the right choice?:dunno:
Do you have an sct tuner? If not, you may consider it with some good mild tunes tow or street Much cheaper than gears. It won't be sluggish anymore :woot:
 

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I have a 2005 6.0L crew cab short bed and I recently added larger rims and tires. The truck got real sluggish and my MPG is at 10. I'm assuming the fix will need to come via gears, if the stock gears on my truck are 3.73's my guess would be to add 4.10's for the new set up.

The new tires I'm running are 325/60/18, are 4.10's the right choice?:dunno:
4.10s are the right gears for those tires. It would actually be a little too much gear (kind of like 4.30s with 35s) but based on what is available it is the next size up and would be close enough. The thing to keep in mind though is I have yet to see/hear of anyone who regeared their truck and actually regained mileage back. You will most certainly gain low end torque and maybe some mileage if you only drove in the city but if you do any driving on the hwy I wouldnt think you would gain much if anything at all. I could be wrong. JMO.
 

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4.10s are the right gears for those tires. It would actually be a little too much gear (kind of like 4.30s with 35s) but based on what is available it is the next size up and would be close enough. The thing to keep in mind though is I have yet to see/hear of anyone who regeared their truck and actually regained mileage back. You will most certainly gain low end torque and maybe some mileage if you only drove in the city but if you do any driving on the hwy I wouldnt think you would gain much if anything at all. I could be wrong. JMO.
Yea I was thinking 4.30 might be too much gear on the highway for a diesel on 35's. I have 4.10's in my Rubicon on 35's and it's kind of sluggish above 50mph, but I know it doesn't have near the torque lol. I ran 4.88's in my old CJ on 36's and it hold plenty of pep! But i was in 4th gear by 40mph.
 

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I just measured my 325.60r20 and they are 35.5 in and they are bigger then my 35's that I am running.
 

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Yes I'm in San Diego...

I'm actually looking for a spare tire for an extra rim I have, let me know if you're interested in selling a tire or two.
 

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I'm running 4.30s and love em. You down in sd? If your near Anaheim you can try my truck with the 4.30s

And I believe the 325.60 is like a 36in tire I have two n my garage.
Yes I'm in San Diego...

I'm actually looking for a spare tire for an extra rim I have, let me know if you're interested in selling a tire or two.
 

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Yea I was thinking 4.30 might be too much gear on the highway for a diesel on 35's. I have 4.10's in my Rubicon on 35's and it's kind of sluggish above 50mph, but I know it doesn't have near the torque lol. I ran 4.88's in my old CJ on 36's and it hold plenty of pep! But i was in 4th gear by 40mph.
If one is towing A LOT, I wouldnt think it is too much gear. I just think it is a waste if one only tows every so often and drives around empty the rest of the time because cruising rpms will about 200 higher than with 4.10s and I see putting in 4.10s to get back to a stock tire/gear relationship. JMO.
 

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I've wondered how 4.30's would do with a 35/36 inch tire. I have pondered the idea of putting them in my truck to get some mileage back. I didn't know if it would hurt or help mpg, I know it'd be a lot stronger down low.
We own a transport company so towing and mileage are foremost with us. Larger tires / wheels are heavy, larger rotational mass equal less mileage at highway speeds. Changing diff gearing will restore the OEM rpm at say 65 mph, but will have little to no effect on mileage. The main culprit is increased frontal aerodynamic resistance from lifting the truck.
As to gearing, 4:10 is so close to 3:73 that its not really worth the effort…If your wanting an increased low rpm benefit, 4:30 or 4:56 would help in towing long grades with 35" tires. The F350 Tow Boss has 4:30 stock, believe it or not, the rpm difference in 3:73 and 4:30 is very close once OD is used.
Of course the penalty for gearing is reduced cruising speed, and that’s something few are willing to do?
W
 

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I also tow a toyhauler a few times a year, are 4.30's better for towing?
Yup way better.nthese trucks came from factory with 4.30gears and this thing is very drivable on the fwy. Actually you drive up here u can have the tire for free and still test my truck before you drop the coin on gears
 

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I just measured my 325.60r20 and they are 35.5 in and they are bigger then my 35's that I am running.
Re-read what you just posted and then compare that to what he's running...

You = 325.60R20
Him = 325.60R18

That makes a BIG difference.
 

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My father and I use to have identical 2008 V10s his had 373s and mine had 430s we really didn't see much difference in mpgs unloaded, it was less than .4 but mine got about 2 mpg better pulling the same weight. Oh ya we both had 315/70R18 tires. Hope this helps.
 

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My father and I use to have identical 2008 V10s his had 373s and mine had 430s we really didn't see much difference in mpgs unloaded, it was less than .4 but mine got about 2 mpg better pulling the same weight. Oh ya we both had 315/70R18 tires. Hope this helps.
Even though you are talking gassers, that is great information. It proves that the mechanical advantage is particularly important while towing and can improve mileage. I'm pretty close to having the wife convinced... Maybe I can get her to swing me an early Father's Day gift... :hehe:
 

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I want 4.30's for my truck and I run 295/65/20 trail grapplers which work out to be a 35.5x12x20. I need some gearing to keep the truck from lugging. It's on my list of things just like better differentials.
 
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