37's + 3.73 rear axle = Sluggish acceleration?

[RAMYOU]

anybody running 37 inch tires? What is the best gear for 37 inch tires with 6.4 hemi? is 4.10 going to be too much RPM? what do u guys think? I am getting closer and closer to getting my truck so many things to consider before I choose the right one

 

[Diminus]

4:10s would be by far the best if they are available for your model , if not get the 3.92s and call it a day

 

[BlackRamHemi]

Your basically pushing 100 pounds more rubber with an effective gear ratio of 3.32:1

(old tire size/ new tire size) x current ratio = effective gear ratio

33/37 = .8919 x 3.73 = 3.32

To get your performance back reverse the equation

37/33 = 1.1212 x 3.73 = 4.18

So you would need a 4:10 to help get you back into the powerband,
However, you should probably add a little more to make up for the heavier tires.

I would do 4.56'

 

[Little Red]

Your basically pushing 100 pounds more rubber with an effective gear ratio of 3.32:1

(old tire size/ old tire size) x current ratio = effective gear ratio

33/37 = .8919 x 3.73 = 3.32

To get your performance back reverse the equation

37/33 = 1.1212 x 3.73 = 4.18

So you would need a 4:10 to help get you back into the powerband,
However, you should probably add a little more to make up for the heavier tires.

I would do 4.56'

Thanks for the math. Helps a lot.

 

[BlackRamHemi]

Thanks for the math. Helps a lot.

Well that's the quick and easy,
if you really want to jump down the rabbit hole,
you have to also consider the additional rotational mass of a larger heavier tire
is on the outside diameter, and has a huge factor on performance too.

That's why I say 4.56's

That's all I ever ran when I had 37's on Jeep's that came with stock 3.73 gears




If I had the money I would swap my ****** 3.55's for 4.10's or maybe even 4.56's into my 4x4 Ram,
and its lowered with just 32" tall A/T tires for street, 28" drag radials for the track.

 

[SIhemi]

Black hemi. My truck has 3.92 and I put on the srt 22" rims with 305/45 tires. If I want to change gears is it worth going 4.10's or just jump to 4.56. I don't know if going up to 4.20's is worth it.

 

[BlackRamHemi]

Black hemi. My truck has 3.92 and I put on the srt 22" rims with 305/45 tires. If I want to change gears is it worth going 4.10's or just jump to 4.56. I don't know if going up to 4.20's is worth it.

O-M-G! never make such a small incremental jump!
3.92's to 4.10's would be barely even noticeable.

Your RPM would go up 5% ,
so you may see about 100 rpm higher at 60mph

4.56's or not at all IMHO for you sir!

 

[SIhemi]

O-M-G! never make such a small incremental jump!
3.92's to 4.10's would be barely even noticeable.

Your RPM would go up 5% ,
so you may see about 100 rpm higher at 60mph

4.56's or not at all IMHO for you sir!

That's what I've been thinking it's not worth such a small jump. Will the 4.56 make a big difference on the hwy.

 

[Little Red]

Well that's the quick and easy,
if you really want to jump down the rabbit hole,
you have to also consider the additional rotational mass of a larger heavier tire
is on the outside diameter, and has a huge factor on performance too.

That's why I say 4.56's

That's all I ever ran when I had 37's on Jeep's that came with stock 3.73 gears




If I had the money I would swap my ****** 3.55's for 4.10's or maybe even 4.56's into my 4x4 Ram,
and its lowered with just 32" tall A/T tires for street, 28" drag radials for the track.

Sweet looking TJ. More of a YJ and XJ man, myself, but that's still a beast.

 

[Diminus]

Has ram offered anything other then the 3.55 and 3.92 with the damn welded on gear? I'm stuck with 35s and 3.55 gears only option I was told I can do is go to factory 3.92 which is not cheap. I wants 37s

 

[RAMYOU]

Your basically pushing 100 pounds more rubber with an effective gear ratio of 3.32:1

(old tire size/ new tire size) x current ratio = effective gear ratio

33/37 = .8919 x 3.73 = 3.32

To get your performance back reverse the equation

37/33 = 1.1212 x 3.73 = 4.18

So you would need a 4:10 to help get you back into the powerband,
However, you should probably add a little more to make up for the heavier tires.

I would do 4.56'

Good stuff Blackramhemi. Thank you everyone. So I'll definitely go with the 4.10s. Now I have to figure out a way to check if the truck really has 4.10s or not. Its hard sometimes to trust these dealership sales people.

 

[doz]

I dont think there was a 4.10 option on the 2014 unless it was an R/T??

I might be wrong. I know the 3.92 were an option which is what I have. There should be an option code (look-up your VIN or check your sticker).

 

[RLJ10X]

The 3.73s in my 14 Jeep Wrangler with the 6 speed manual, and 33" tires are lower than the 4.10s in my Ram.

My 5.7, 4.10s with a 545RFE, and 33"s will spin the engine 1600 rpm at 55 mph. In my never to be humble opinion, 4.10s should have been standard. All the knuckle heads that decided to gear these trucks taller than that should be fired. 4.10s are just a smidge tall, if you ask me.

If I was running 37s, I'm not sure I wouldn't go deeper than 4.56s, at least with the 545.

There has to be someone with first hand experience with 37s and 4.56s.

 

[BlackRamHemi]

FYI

The OP stated he has a 6.4L
That means he has a 2500 HD Ram with solid front axles front and rear.
The auto trans is a 6 speed 66RFE, 3.73's are standard for the SLT
4.10's are standard for the Outdoorsman

 

[doz]

eRRR, missed that my bad. Even still, 4.10 on 37" tires will be kinda lame lol. Id try to go 4.56

 

[loveracing1988]

With the 6.4 I would go to 4.56's before going to 4.10's. With a Cummins 4.10's would be fine but those 37's take a lot of power to spin.

 

[RAMYOU]

...

 

[RAMYOU]

With the 6.4 I would go to 4.56's before going to 4.10's. With a Cummins 4.10's would be fine but those 37's take a lot of power to spin.

So. 4.56 is after market?

 

[TWILLIAMS9]

I have the 4.10's with my 37's. I must say its not bad and one can certainly deal with it, however it did take away quite a bit of performance. I got a quote for a 4.56 install and it was $2300! That is with OEM gears that are supposedly far superior than aftermarket gears. I wish I could get a 4.88 however because of our front AAM 9.25 axle 4.56 is the lowest available gear. I plan to get 4.56 gears installed in the distant future, just too many other things I have to take care of in the mean time than spend more money on my already new truck.

 

[Diminus]

I failed to noticed he was purchasing a diesel lol I'm stick on 3.92 max front diff with the 1500 .... Designers **** the bed on that one...