42RLE automatic and 31 inch tires

[trevino33]

Hey everyone, I am about to go and purchase some 31-inch tires for my tj tomorrow. I believe I have stock gears at 3.07 and the automatic 42rle transmission. I went and checked underneath but the tag was missing so cannot guarantee ratio as I am third owner. I have an 06 X. I am going to purchase some used wheels and tires for 200 dollars that are in good shape and have a lot of life left in them before going out and purchasing a full brand new set to ensure it will drive ok. I am currently running 33-inch tires and it is unbearable. Does anyone have any experience with this setup? I also have a 3 suspension lift and 1.25 inch body lift. I know it will look really funny but if I like how it drives with 31s I will be lowering it. Thanks!

 

[Thunderhead]

3.07’s suck in general but will be just fine with 31’s
If you like them maybe just take out the body lift and see how it looks.

 

[Chris]

3.07 is literally the worst gear ratio ever installed in a TJ. Even with 31s it will suck even more than it does now.

 

[JEEPCJTJ]

the 31 inch tires may not be perfect but they will be less unbearable than 33s. Losing some lift will help the looks.

 

[trevino33]

3.07 is literally the worst gear ratio ever installed in a TJ. Even with 31s it will suck even more than it does now.

Hhaha yes they do suck but I am no position to regear in the next few months.. How will it suck even more?

 

[MountaineerTom]

With 3.07, 31’s may not be great but should be better than 33’s.

Turning the O/D off will help you some.

 

[Chris]

Hhaha yes they do suck but I am no position to regear in the next few months.. How will it suck even more?

Well considering the nature of the 42RLE and and how it likes to be geared very deeply the larger tires you go with, I’m just saying it’s going to be more of a pig to drive. But if you can deal with it the way it is now, you should be fine. This is one of those cases where you won’t actually know just how much it sucks until you re-gear, then it will all dawn on you.

 

[TheBoogieman]

I believe I have stock gears at 3.07. I also have a 3 suspension lift and 1.25 inch body lift. I know it will look really funny but if I like how it drives with 31s I will be lowering it. Thanks!

Put your VIN# in here to get an instant build sheet.
Equipment Listing (force.com)

 

[MountaineerTom]

Well considering the nature of the 42RLE and and how it likes to be geared very deeply the larger tires you go with, I’m just saying it’s going to be more of a pig to drive. But if you can deal with it the way it is now, you should be fine. This is one of those cases where you won’t actually know just how much it sucks until you re-gear, then it will all dawn on you.

He’s moving down from 33’s to 31’s. Should be some improvement, although not ideal.

 

[Chris]

He’s moving down from 33’s to 31’s. Should be some improvement, although not ideal.

Yes, I just think that 3.07 and a 42RLE is going to suck balls with any tire size. I mean mine sucked with 4.10 and 31s

 

[MountaineerTom]

Yeah, not ideal, but for the OP it may feel like a huge improvement.

 

[trevino33]

thanks for all of the responses, I am hoping it will be some what of an improvement. It should be as these new ones are all terrains and the current 33s are mud terriains..

 

[trevino33]

Yeah, not ideal, but for the OP it may feel like a huge improvement.

Hopefully at least a little improvement in city mpg lol it's ok on the highway seems to get around 13 low 14 , but in town, it seems to get around 8-10mpg.. it's ridiculous. a trip the store across town takes an eighth of a tank,..

 

[jmbstudios]

Not trying to derail the thread but I have a question about that build sheet site.
When it lists all that your jeep has and then says Optional Equipment, does that mean your jeep has those options or those are just all available?

 

[trevino33]

Update:

I ended up finding some basically brand new Ko2s for a really good deal, they are 31x10.50x15 on some stock wheels that I plasti dipped black. I absolutely love it and can only imagine how nice it must be to drive a properly geared TJ. It does look a little funny because I am on a 3-inch suspension lift and 1.25-inch body lift. I am going to remove the body lift when I have some time. Here is a picture. I still need to peel plasti dip off tires but all in all for very little prep, I think it looks pretty good.

 

[someguysjeep]

1 might consider leaving the BL and taking 1" out of the suspension. if 1 day you ever wanted a shallower belly pan.

 

[Hokahay]

With 3.07, 31’s may not be great but should be better than 33’s.

Turning the O/D off will help you some.

I have 5.13 and 33s with a 42RLE. I turn off the overdrive lugging around town even still!

 

[SolarColumbia]

I'm thinking you may have 3.73 gears. I don't think the 3.07 gears ended up in 42rle Jeeps very often.

 

[Jerry Bransford]

I went and checked underneath but the tag was missing

The ratio tags on both axle differential covers were both missing?

 

[trevino33]

The ratio tags on both axle differential covers were both missing?

Yes sir. When I checked in the garage at my parents a while back couldn’t find anything. I’ll check again when the snow melts away here.