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An Engineer's Ultimate Guide To 3.21 VS 3.92 Axle Ratio

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deeve

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Oh man. I ordered 3.92 with mine, but now I’m wondering if I made a mistake. These MPG stories have me worried. I didn’t do great in physics class, but I think I could make up for the bad gearing choice with larger tires. Anyone have an idea on how big I’d have to go to offset then 3.92, or am I thinking about it incorrectly?
















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HSKR R/T

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Oh man. I ordered 3.92 with mine, but now I’m wondering if I made a mistake. These MPG stories have me worried. I didn’t do great in physics class, but I think I could make up for the bad gearing choice with larger tires. Anyone have an idea on how big I’d have to go to offset then 3.92, or am I thinking about it incorrectly?
















😜
Definitely 6" lift with 37s and you should be good
 

Redfour5

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Oh man. I ordered 3.92 with mine, but now I’m wondering if I made a mistake. These MPG stories have me worried. I didn’t do great in physics class, but I think I could make up for the bad gearing choice with larger tires. Anyone have an idea on how big I’d have to go to offset then 3.92, or am I thinking about it incorrectly?
















😜
If you do NOT tow, live in a flat state where it never gets below 40 degrees, the 3.21's are perfect. I live in MT, had a 2013 3.55 and a 2015 3.92 and now a 2021 3.21. I tow a 6700 lb travel trailer...and did I mention I live in Montana... Oh, I see I did... I wish I had my 3.92 back. The 3.21 is...adequate... The towing mileage is virtually no different but the transmission and engine work completely differently and much harder. Now, on a now wind sunny day running down one of the valley routes and a good road, I've definitely seen 22 mpg with the 3.21, but that is a rare occasion... I do NOT understand why any dealer would build a truck to tow (full tow package) and order the 3.21's. OBVIOUSLY, whomever orders trucks at that dealership doesn't get it and gee, saved 95 bucks...
 

deeve

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Yep. This is going to be my do anything/everything truck so I think 3.92 will be perfect. If I hate it or really need that extra mpg or two I could always regear.
 

TNRamGuy

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Yep. This is going to be my do anything/everything truck so I think 3.92 will be perfect. If I hate it or really need that extra mpg or two I could always regear.
Jay leno might be the only person that has ever regeared anything. But you are correct 3.92 is perfect
 

deeve

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Jay leno might be the only person that has ever regeared anything. But you are correct 3.92 is perfect
Well, most of my experience off-road comes from Jeeps where regearing is not uncommon. Not that this will be an off-road rig but it will see the occasional trail I think.
 

HSKR R/T

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Well, most of my experience off-road comes from Jeeps where regearing is not uncommon. Not that this will be an off-road rig but it will see the occasional trail I think.
If it's 4wd, regearing isn't a cheap option as you have to replace the entire front axle. You can't just swap the gear set out
 

TNRamGuy

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Well, most of my experience off-road comes from Jeeps where regearing is not uncommon. Not that this will be an off-road rig but it will see the occasional trail I think.
Has anyone ever "regeared" any vehicle? While this may have been common in the 60's I would have to believe it is long gone
 

ferraiolo1

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Lol no it’s still a thing. Especially on cars and off-road vehicles.

Or people who buy the wrong truck and think it will increase their towing capacity.


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TNRamGuy

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I mean, I am pretty much a gear head, and don't know anyone other than my 70 yo dad that has ever "swapped gears"
 

TNRamGuy

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Lol no it’s still a thing. Especially on cars and off-road vehicles.

Or people who buy the wrong truck and think it will increase their towing capacity.


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So while I get that you love to argue, your answer is still 'no'
 
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