38s or 40s on a 1500 QC with 8" of lift

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FirePower

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So I will be going with either a rough country or zone 5" suspension lift plus a 3" performance accessories body lift soon. And I will be leveled in the front.
I want to run 38x14.50 or 40x15.50

Can I clear these without rubbing at full turn or doing any cutting if I get wheels with a -44 offset?

If not which offset could I use to push them out far enough to clear them?

Truck is 03 qc 4x4 hemi
 

justin13703

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We will also need to know the wheel width to give an accurate response as far as rubbing.

A 40x15.5 tire is going to suck a massive amount of power from your truck
 

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You should clear the 38's with the combo of those lifts, idk about the 40's. I hope regear tho like Justin said cause that thing will be a **** with those tires.
 
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FirePower

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You should clear the 38's with the combo of those lifts, idk about the 40's. I hope regear tho like Justin said cause that thing will be a **** with those tires.

We will also need to know the wheel width to give an accurate response as far as rubbing.

A 40x15.5 tire is going to suck a massive amount of power from your truck

Not sure, was going to go with 15 or 17", 9 to 12" width.

My gearing is factory, 3.92 I believe.

Wasn't going to do any serious wheeling. Wasn't planning on regearing.

Just for my information what would my factory gearing and those tires be like? Which gearing would be ideal for 38 to 40s? And how much would it cost parts and labor?
 

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I'd definitely go with the Zone 6" kit with 5" rear coils + the PA 3" body lift . With bilsteins 5100s up front @ +2.8 " .
This will give about 9 -9.5 " of lift up front because the 6" kits just give about 4.5" of true lift in the front .
With 9-9.5" up front and a 12" +wide wheel with a -24mm+ offset .... I'd say you'll fit the 38s not sure on the 40s without some trimming

This info is only based off what I've read on the forum.

I'd also be investing in some 456 differentials to help with power loss .

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FirePower

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I'd definitely go with the Zone 6" kit with 5" rear coils + the PA 3" body lift . With bilsteins 5100s up front @ +2.8 " .
This will give about 9 -9.5 " of lift up front because the 6" kits just give about 4.5" of true lift in the front .
With 9-9.5" up front and a 12" +wide wheel with a -24mm+ offset .... I'd say you'll fit the 38s not sure on the 40s without some trimming

This info is only based off what I've read on the forum.

I'd also be investing in some 456 differentials to help with power loss .

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Could you post a link to the 6" kit? All I've been able to find for my truck is the 5" zone kit.
 

R.L.K.

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Damn , I didn't see you were an 03 I thought you were a 4th gen ...my bad .
I'm sure there's 6 or 8" kits available for your year .

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5.13s an you'll be g2g lol
 

justin13703

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Not sure, was going to go with 15 or 17", 9 to 12" width.

My gearing is factory, 3.92 I believe.

Wasn't going to do any serious wheeling. Wasn't planning on regearing.

Just for my information what would my factory gearing and those tires be like? Which gearing would be ideal for 38 to 40s? And how much would it cost parts and labor?

A 15 or 17 inch wheel imo would be pretty small for a 40 inch tire if it's not being used for offroading. That's a lot of sidewall and it is probably going to ride and handle like crap.

With tires that size I would regear to at least 4.56. Those size tires and wheels with 3.92s will be an absolute pig. You will have no power and get all of 2-3mpg lol.
 
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FirePower

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A 15 or 17 inch wheel imo would be pretty small for a 40 inch tire if it's not being used for offroading. That's a lot of sidewall and it is probably going to ride and handle like crap.

With tires that size I would regear to at least 4.56. Those size tires and wheels with 3.92s will be an absolute pig. You will have no power and get all of 2-3mpg lol.

I like the look of the meat of the tire on smaller wheels, I figured the more sidewall the softer the ride would be?

Where can I find gears for the truck and how hard is it to replace them?
 

R.L.K.

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You can find gears at many places , I'd try Moe's Performance first .

If you've never done this kind of work then you definitely need to pay a shop to do it !
What gears do you have now ?

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FirePower

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You can find gears at many places , I'd try Moe's Performance first .

If you've never done this kind of work then you definitely need to pay a shop to do it !
What gears do you have now ?

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Okay I'll look into Moe's

I'm mechanically inclined but I'd just pay a shop to do it

I have factory gearing, I believe it's 3.92
 

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If you only go to 37" tires and run a 17" alluminum wheel you'll be able to run your 392 gears just fine . This way you can save up $$ for gear swap when your 37s wear down then upgrade to 38s or 40s and install some 456 , 513 or 579 differentials in the future ...

If you go lower than 456 ring & pinion gears you may have to Chang the rear end & front end as lower gears like 513s or lower may not fit ...not sure ?

Just to be clear I'm not positive ring & pinion gears lower than .456 are even available for your differentials.

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Csanders1992

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I like the look of the meat of the tire on smaller wheels, I figured the more sidewall the softer the ride would be?



Where can I find gears for the truck and how hard is it to replace them?



A taller sidewall also means more give in turns. It'll feel unstable when your turning


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FirePower

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If you only go to 37" tires and run a 17" alluminum wheel you'll be able to run your 392 gears just fine . This way you can save up $$ for gear swap when your 37s wear down then upgrade to 38s or 40s and install some 456 , 513 or 579 differentials in the future ...

If you go lower than 456 ring & pinion gears you may have to Chang the rear end & front end as lower gears like 513s or lower may not fit ...not sure ?

Just to be clear I'm not positive ring & pinion gears lower than .456 are even available for your differentials.

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I'm pretty sure I have 3.92s but I'll double check

Would I see that big of a difference between 37x13.50 and 38x14.50?
 

R.L.K.

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I'm pretty sure I have 3.92s but I'll double check

Would I see that big of a difference between 37x13.50 and 38x14.50?
The weight Mass of the tire & Wheel to get moving is where the seat of the pants loss of power is , so would you see that much difference?

Well people say and I certinly can attest to this : as litle as 6 lbs increase in a wheel and tire combo is enough to feel a diff and 10 lbs is imo a sizeable seat of the pants loss of power .
I've ran 36s , 38s , 40s , 42s & 44" X 18" Supper swampers on 3 diff vehicles and I felt a diff with each and ended up regearing twice and going down in tire size the other .

This is why I suggest 17" max of 18" alluminum wheels because the added wheel diameter , alluminum or steel out weighs the tiers rubber wt in almost every situation.

Another noticable difference ( seat of the pants) is passing , but let's face it with 38" + tires no one expects to gear down and leave people in a cloud of dust the main place you feel the loss will be in stop n go type driving .

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FirePower

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The weight Mass of the tire & Wheel to get moving is where the seat of the pants loss of power is , so would you see that much difference?

Well people say and I certinly can attest to this : as litle as 6 lbs increase in a wheel and tire combo is enough to feel a diff and 10 lbs is imo a sizeable seat of the pants loss of power .
I've ran 36s , 38s , 40s , 42s & 44" X 18" Supper swampers on 3 diff vehicles and I felt a diff with each and ended up regearing twice and going down in tire size the other .

This is why I suggest 17" max of 18" alluminum wheels because the added wheel diameter , alluminum or steel out weighs the tiers rubber wt in almost every situation.

Another noticable difference ( seat of the pants) is passing , but let's face it with 38" + tires no one expects to gear down and leave people in a cloud of dust the main place you feel the loss will be in stop n go type driving .

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Oh okay I see what you're saying.

When you had the 38s and 40s did you have the 4.56s or something else?
 

R.L.K.

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Oh okay I see what you're saying.

When you had the 38s and 40s did you have the 4.56s or something else?
On a Chevy I believe it was 373 diffs this is the one I dropped down to 38s .

On a 85 Toyota I had 411s I dropped down to 40s from 42s

On a 79 Toyota I had 44s ( highly modified truck ) lot of custom work I had 571 differentials , I could bark the 44 x 18s shifting manually.
571 gears , had a built 231 Buick V-6 bored. 040" with a 280 comp. cam a 350 Turbo auto xsmn with a shift kit . I broke U joints and axles on a regular basis but it was a fun truck to build and drive . I slung a lot of mud with that truck & it would almost float with the 44s , don't ask how I know .
This is going back nearly 30 years

My current truck(2014 Ram ) is the first 4x4 I've ever owned that I did not lift with a minimum of 36" tires before making the first payment on it in my life LOL .
Kinda funny I'm thinking of 35s with a 4 or 6" BDS lift only on this truck as it's my daily driver

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FirePower

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On a Chevy I believe it was 373 diffs this is the one I dropped down to 38s .

On a 85 Toyota I had 411s I dropped down to 40s from 42s

On a 79 Toyota I had 44s ( highly modified truck ) lot of custom work I had 571 differentials , I could bark the 44 x 18s shifting manually.
571 gears , had a built 231 Buick V-6 bored. 040" with a 280 comp. cam a 350 Turbo auto xsmn with a shift kit . I broke U joints and axles on a regular basis but it was a fun truck to build and drive . I slung a lot of mud with that truck & it would almost float with the 44s , don't ask how I know .
This is going back nearly 30 years

My current truck(2014 Ram ) is the first 4x4 I've ever owned that I did not lift with a minimum of 36" tires before making the first payment on it in my life LOL .
Kinda funny I'm thinking of 35s with a 4 or 6" BDS lift only on this truck as it's my daily driver

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Damn you've had a lot of trucks.

So I decoded my vin, and it says I have 3.55 min and 3.92 max for the front and the rear.

What does that mean? How can there be two?
 

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That just means you have one or the other .
There's dodge sites that you can get your build sheet , this will show you what your truck left the factory with.
Other than that , you could remove the diff cover and & count the teeth on the ring & pinion gears then divide the # of teeth from the ring gear by the # of teeth on the input pinion gear .

Example = 41 teeth on the ring ÷ 10 teeth on the pinion gear = 4.10 gear ratio .
Hope this helps !

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