37's and 3.21. Here I go again...

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Hey everyone. I've finally decided I want to do a six inch lift with 37's on my 2015 Ram 1500. I see posts that say it is an absolute dog and those few rare posts that say 3.21 with 37's don't seem to be an issue whatsoever. I feel like I am way too stuck on 37's and how nice they look. But I want to make sure I'm not going to tear things apart in a month. I have the 8 speed tranny (of course) which I've heard helps a little bit of the 6 speeds. I don't live in a hilly area but I do end up driving up and down some hills every once in a while. I would say my driving is 75% city and 25% highway. But when I say city I mean country roads that are 55 MPH and are usually a few mile strips. I get everyone says not to but the people who say not to never had any experience with the setup. I guess that's why i'm still stuck on 37's. I also don't get why it isn't just like a load from a trailer. I get there is more revolutions but I feel like it can't be that big of an issue... Any input is appreciated.
 

RedSRT4Me

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Hey everyone. I've finally decided I want to do a six inch lift with 37's on my 2015 Ram 1500. I see posts that say it is an absolute dog and those few rare posts that say 3.21 with 37's don't seem to be an issue whatsoever. I feel like I am way too stuck on 37's and how nice they look. But I want to make sure I'm not going to tear things apart in a month. I have the 8 speed tranny (of course) which I've heard helps a little bit of the 6 speeds. I don't live in a hilly area but I do end up driving up and down some hills every once in a while. I would say my driving is 75% city and 25% highway. But when I say city I mean country roads that are 55 MPH and are usually a few mile strips. I get everyone says not to but the people who say not to never had any experience with the setup. I guess that's why i'm still stuck on 37's. I also don't get why it isn't just like a load from a trailer. I get there is more revolutions but I feel like it can't be that big of an issue... Any input is appreciated.

From experience the weight of the 37" tire is going to be heavier than a stock rim/tire combo. That's where your power loss will come from.
 

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Talk to member SoCal about 37's and the reason he changed gears and what type of difference it made.
Jay
 

Firebird

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3.21 gears are a dog with stock wheels and tires, cannot imagine adding 37's
 
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From experience the weight of the 37" tire is going to be heavier than a stock rim/tire combo. That's where your power loss will come from.

No I get that. Each wheel and tire stock is around 82 pounds. Which is 328 for four. The new rims and tires will be 460 pounds. It’s only 130 pounds more which doesn’t seem like something my truck couldn’t handle right now.
 

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I had 3.21s and 37s and I didn't mind it to bad. Where it did bother me was the constant downshifting on the Hwy and the slightest hill. I went with the lightest 37" tire I could find and I honestly didn't feel much more power loss than my 34" x11.5" E rated Nittos I had prior. I only ran it for about 6 months before I totaled my truck but I definitely enjoyed it. Road trip to the outer Banks faired well with summer gas @ 18mpgs on the evic and a hill laden trip to upstate NY 16mpgs. I can't comment on any drivetrain issues etc bc I hadn't had the time to experience any but in the time I had it roughly 5k miles all seemed solid and fine. Tranny temps stayed consistent(avg 185-188) never over 192 and engine temps were always normal. Unless you like to constantly drop the hammer and feel "the power" then I don't think it'll bother you. I never expected a ton of power in a truck so I guess that's why it never bothered me. If I wanted to go fast and take off like a bat outta hell I would've bought a sports car. Just my two cents, I was running 18x9 XD monsters with 37x12.5 BFG km2s

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I wouldn't do it. Here is my story: I owned an old school '92 full size Blazer 4x4 for years. I loved it it. After about a year of owning, I put a 6-in lift on it and ran 35s on stock 3.73 gears. The transmission was constantly downshifting on both highway small hills. You got to think about the additional wear and tear that causes on a transmission. My transmission did eventually need to be rebuilt after dropping 1st and 3rd. I couldn't imagine 3.21 on 35s, nevermind 37s! I ended up re-gearing to 4.56s and it was a huge difference in performance and driveability. The HD 14 bolt rear was also nice w/a Detroit locker. I could get out of anywhere w/out engaging 4wd. That was nice! I would not run 37s without re-gearing. It is a world of difference!
 
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I had 3.21s and 37s and I didn't mind it to bad. Where it did bother me was the constant downshifting on the Hwy and the slightest hill. I went with the lightest 37" tire I could find and I honestly didn't feel much more power loss than my 34" x11.5" E rated Nittos I had prior. I only ran it for about 6 months before I totaled my truck but I definitely enjoyed it. Road trip to the outer Banks faired well with summer gas @ 18mpgs on the evic and a hill laden trip to upstate NY 16mpgs. I can't comment on any drivetrain issues etc bc I hadn't had the time to experience any but in the time I had it roughly 5k miles all seemed solid and fine. Tranny temps stayed consistent(avg 185-188) never over 192 and engine temps were always normal. Unless you like to constantly drop the hammer and feel "the power" then I don't think it'll bother you. I never expected a ton of power in a truck so I guess that's why it never bothered me. If I wanted to go fast and take off like a bat outta hell I would've bought a sports car. Just my two cents, I was running 18x9 XD monsters with 37x12.5 BFG km2s

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Thanks I really appreciate to hear this. Sorry to hear that you totaled your truck and I hope you're okay from when it happened. I feel I have close to the same feeling to you that if I wanted something fast it would've been a sport car but I like my "big" trucks and I want to enjoy having a big truck. I'm not in it for speed or insane power.
 
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I wouldn't do it. Here is my story: I owned an old school '92 full size Blazer 4x4 for years. I loved it it. After about a year of owning, I put a 6-in lift on it and ran 35s on stock 3.73 gears. The transmission was constantly downshifting on both highway small hills. You got to think about the additional wear and tear that causes on a transmission. My transmission did eventually need to be rebuilt after dropping 1st and 3rd. I couldn't imagine 3.21 on 35s, nevermind 37s! I ended up re-gearing to 4.56s and it was a huge difference in performance and driveability. The HD 14 bolt rear was also nice w/a Detroit locker. I could get out of anywhere w/out engaging 4wd. That was nice! I would not run 37s without re-gearing. It is a world of difference!

I get what you are saying but it's not my setup and it was from 1992. I have nothing against that but It's not my setup and I feel that's too broad of a gap to make me really think about it.
 
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That is also what I keep asking people, if these trucks are meant and "CAN" tow/haul anywhere from 4,000 to 10,000 lbs ... someone please explain to me the difference from 37, 38 or 40" wheels and towing 4,000 to 10,000 lbs ... funny that Wyatt mentioned that because we were talking about this very topic at work during lunch ... just makes no sense ...
 

HDHNTER

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That is also what I keep asking people, if these trucks are meant and "CAN" tow/haul anywhere from 4,000 to 10,000 lbs ... someone please explain to me the difference from 37, 38 or 40" wheels and towing 4,000 to 10,000 lbs ... funny that Wyatt mentioned that because we were talking about this very topic at work during lunch ... just makes no sense ...


Rotational mass = https://www.w8ji.com/rotating_mass_acceleration.htm
 
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Oh man ... now that is some good stuff lol ... makes and makes no sense at the same time ... good knowledge though my Man ...thank you
 

skyline090

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I get what you are saying but it's not my setup and it was from 1992. I have nothing against that but It's not my setup and I feel that's too broad of a gap to make me really think about it.

Putting 37"s on any truck running anything less than 4.xx gears isn't wisest decision. Do you want the look more than practicality and reliability? I ran 33s, on my '12 JK (3.21s) and even with the manual trans it was a dog. A full size pickup, with the same motor; more weight, more frustration.

4447d1264289351-gear-ratios-gear_ratios.jpg
 
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Man this is rough lol ... I am not looking for a speed Demon or looking to tow and haul anything ... Yes I like the look of a 7" lift with 37s, hell I really want 40"s but I know I would be really asking for trouble then ...

I have yet to meet someone around here that has 37s and even 40s that is not running 4.XX's and is having issues with their trucks ...
 

HDHNTER

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Oh man ... now that is some good stuff lol ... makes and makes no sense at the same time ... good knowledge though my Man ...thank you


Rotational weight increases w/ centrifugal force. I think the rough math is something along the lines of 1lb of rotational weight is equal to approximately 7lbs of static weight, so say you have a tire/wheel combo that's 40lbs heavier per corner than OEM - that's essentially the equivalent of 280lbs of extra weight per corner.... 1120lbs of extra ass to move is going to be felt wickedly bad w/ the V6.
 
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Rotational weight increases w/ centrifugal force. I think the rough math is something along the lines of 1lb of rotational weight is equal to approximately 7lbs of static weight, so say you have a tire/wheel combo that's 40lbs heavier per corner than OEM - that's essentially the equivalent of 280lbs of extra weight per corner.... 1120lbs of extra ass to move is going to be felt wickedly bad w/ the V6.

But I have the V8 .... :crazy:
 

HDHNTER

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Seeing as how yours is a 2wd, re-gearing isn't going to cost you a small fortune compared to a 4wd, if you find the 37s slow you down more than you are willing to live with. That said, I would add a Pedal Commander to the mix before opening up the pumpkin. A tune, exhaust, CAI & Pedal Commander changed my mind on wanting to upgrade to 3.92s. I can spin the 35s w/ my 3.21 LSD as is.... 3.92s would just add more spin to the equation & quicker gear changes. It's worth mentioning I run a relatively light 35 (65lbs per).
 
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