Topic: 31's with 4.56's or 4.88's

[streetmaster]

Anybody running 4.88's with 31's ? For now im running 4.11's with 28" tall P225/75/15 Wrangler GSA's, and i loose a little pep on long grades. If i install 31's with the 4.11's, i would drop about 2-300 rpms, and the performance with my 2.4L will suck. 4.56's with 31's run about the same as 4.11's with 28" tall tires, i just cant justify spending the money to go from 4.11's to 4.56's, but 4.88's are doable.

[Jeffy]

Anybody running 4.88's with 31's ? For now im running 4.11's with 28" tall P225/75/15 Wrangler GSA's, and i loose a little pep on long grades. If i install 31's with the 4.11's, i would drop about 2-300 rpms, and the performance with my 2.4L will suck. 4.56's with 31's run about the same as 4.11's with 28" tall tires, i just cant justify spending the money to go from 4.11's to 4.56's, but 4.88's are doable.

I'd go with 4.88's.  No point going to 4.56's these day's unless you really want to stick with 31's.  Most don't.  Once you regear you'll want 33's and you'll be back in the same boat.  The 2.4L's seem not to take larger tires as easily as the 2.5L's.  Not as much low down torque so going lower would compensate for that.

[joe-joe]

You want to go 4.88's! There is no reason to go 4.56's in a 2.5L. You will really enjoy driving again with the 4.88's.

[Bounty Hunter]

Your thinking is correct, not really worth the time and $$ to go from 4.11 to 4.56.

Make the jump to 4.88, you'll be glad you did.

[streetmaster]

Yeah 31's and 4.56's would run the same as 4.11's and the 28" tall Wrangler GSA's i have on now, which runs a little less than stock on power. I figured that the 4.88's would help my 2.4L scoot down the road a little better that stock on 31's. Id like to go with 32's and 4.88's which would run right at stock performance, but with the greater rotating mass of larger tires, im guessing that that 32's with 4.88's will be a little harder on my 2.4L, than what a stock 27" tire with 4.11's would be because the 32's are heavier than the 205/75/15's even they should both run at stock performance. So i figured 31's with 4.88's instead of 4.56's, to give me a little extra kick in the pants torque over stock performance. I want more pep, but im not willing to drop back down to the 27" 205/75/15's to get it. (Oppinions Please) 

[aw12345]

I beg to differ on this I put 4.56 gears in my 2006 se with the 2.4 engine for 31" tires in my opinion that gearing is definitely low enough it climbs the passes here in So Cali with ease revs 3000rpm at around 70-75 ehich is higher than I like. Right now I have 33" tires on it Cooper sst mudders and I like the rpm range better. It still maintains speed in 6th gear looses a little power compared to the 31" bfg all terains but It is a lot better than the bfg all terains with the stock 3.73 gearing. I would have been very unhappy with 4.88 gears and 31" tires. but then that is my opinion, I hate screaming engines and also it would definitely hurt your milage going from 3.73 gears to 4.56 gears on the 31" tires I lost about 1-2 mpg Putting the 33" tires on does not reallly seem to hurt the milage to bad have to check the speedo still with my GPS with the 31" tires it was 3mph fast at 65 and I think its about 3 mph slow now or dead on but so far the milage seems to be about the same.
Just take this as an opinion, however this is what my little Jeep does on the road not somebodies assumption.
In reality 31" tires and 4.10 gears make a very nice combo for a 2.4 engine

[Jeffy]

I beg to differ on this I put 4.56 gears in my 2006 se with the 2.4 engine for 31" tires in my opinion that gearing is definitely low enough it climbs the passes here in So Cali with ease revs 3000rpm at around 70-75 ehich is higher than I like. Right now I have 33" tires on it Cooper sst mudders and I like the rpm range better. It still maintains speed in 6th gear looses a little power compared to the 31" bfg all terains but It is a lot better than the bfg all terains with the stock 3.73 gearing. I would have been very unhappy with 4.88 gears and 31" tires. but then that is my opinion, I hate screaming engines and also it would definitely hurt your milage going from 3.73 gears to 4.56 gears on the 31" tires I lost about 1-2 mpg Putting the 33" tires on does not reallly seem to hurt the milage to bad have to check the speedo still with my GPS with the 31" tires it was 3mph fast at 65 and I think its about 3 mph slow now or dead on but so far the milage seems to be about the same.
Just take this as an opinion, however this is what my little Jeep does on the road not somebodies assumption.
In reality 31" tires and 4.10 gears make a very nice combo for a 2.4 engine

Your auto is a 6 speed while his is a 4 speed.  The 6 will have better gear splits overall.  If he's sticking to small tires then it would probably be cheaper to get some axles from a Manual with stock 4.10/4.11's and swap complete housings for around $250-500.  Like what was said before though, it's not really worth it to go to 4.56's (well unless you can fome some 2004 axles) unless you want to stick with 31's.  Most people don't and end up moving taller.

I hate being undergeared.

[streetmaster]

I thought that all 05's and 06 SE's with the 2.4L and the 6speeds came stock with 4.56 gears, as apposed to my 04 with the 2.4L, NV1500 5speed, and 4.10's up front, and 4.11's out back. I've been told that my 2.4L will not like 31's with the 4.11's, and the NV1500 5speed. I do know that after swaping out my steel wheels with P205/75/15's for the ECCO's with P225/75/15's from my bosses 05 jeep because he got 31's. My power dropped about 100rpm's, and my OD doesnt hold as well with 1" larger tire on long grades. So i feel that 2" more on top of that would knock the crap out of it.

[Jeffy]

I thought that all 05's and 06 SE's with the 2.4L and the 6speeds came stock with 4.56 gears, as apposed to my 04 with the 2.4L, NV1500 5speed, and 4.10's up front, and 4.11's out back. I've been told that my 2.4L will not like 31's with the 4.11's, and the NV1500 5speed. I do know that after swaping out my steel wheels with P205/75/15's for the ECCO's with P225/75/15's from my bosses 05 jeep because he got 31's. My power dropped about 100rpm's, and my OD doesnt hold as well with 1" larger tire on long grades. So i feel that 2" more on top of that would knock the crap out of it.

From the looks of it, only 2004 Auto have 4.56's.  (Another member was looking into it.)  That still had the 42RHE 4-speed auto though.  The following year, I believe they switch for the MB 6-speed and used 3.73's and continued this till the end of production.

[aw12345]

Yup 2005 and 2006 manual 6 speed uses 3.73 gears. I think gear changes depend a lot on the kinda driving you do
In the mid west or anywhere it is reasonably flat 4.10 gears and 31" tires is close to the stock 28" tires and 3.73 gears. You drive in a fairly mountainous area 31" tires and 4.30 gears would be ideal but hard to realize so you would end up with 4.56 gears which work pretty well for 31" tires might work well for 33" tires but depends on personal preference. I am happy this way others might like 4.88 better. Is definitely a good bey if the idea of 35" tires appeal to you.

[neale_rs]

Sounds like all the above applies to the 2.4 jeeps but in any case I'll share my experience with the 2.5.    The regearing was done from a baseline of 4.10 gears with 30 inch tires, which worked very well for me, could go over overpasses in 5th with no problems.    Regeared to 4.56 in anticipation of going to 32 inch tires, this would give me an effective gear ratio with 32s a bit lower than the 4.1 with 30s.  Currently still running the 30s with 4.56 and like it a lot. I thought it would rev too much but it is actually just fine. So 31s with 4.56 would work very well, and 4.88 with 31s would probably feel about like my 4.56 with 30s which is also fine, especialy with the 2.4 which seems like it needs lower gearing than the 2.5.