31" tires with stock gears

how are 31" tires with stock gears? I believe i have 3.55 would i be able to get away with maybe adding a new intake and exaust instead of changeing the gears all together?

i have the ax15 manual with, i believe 3.07's and 31 is no problem at all. i also have intake and flowmaster and high flow cat with the factory header.

Ive got a 99 with 31's and 3.55 gears and its just fine.
BTW... its an automatic and the motor is bone stock.

i run them and its deffinatly doable
this summer im gonna look in to getting regeared to 4.10 or 4.56

You can run 31s fine with stock 3.55 gears, though some view them a little low and most actually prefer 4.10. You won't have any issues however.


Red_01_XJ, 4.56 would be WAY to high for 31s..

I've been running 31s" w/ 3.55 for almost 4 years. It is acceptable. On the highway, it will shift more going up grades, but just drop it to 3rd, and it isn't that bad.

I too am running 31s with 3.55 gears. Works fine. I will be changing them out to 4.56 but that is in the future and because I am going to 33s. Before you decide on gears think about what you want to do with your XJ in the future. Is it going to be a mostly DD with occasionaly wheeling? Are you planning on bigger tires, etc. I would definitely give these things some consideration before spending the cash on something that you are: 1. Not going to be happy with, 2. Going to replace again soon.Just my .02!

Glen

Okay, so any of you guys running 31's with 3.55's do any towing? I have two quads and with the trailer it's about 1500#'s. Not really heavy but how did you find towing with the above combo? I know I am going to go with 4.10's down the road and I almost have all the parts for my 3" lift but I don't want to lose the ability to tow while I am waiting for the funds for the gears.

BTW, I live in San Diego so most of my towing is having to go through the mountains to get to the desert so not a whole lot of flat land towing.

Comments welcomed! Thanks guys.

helix said:

You can run 31s fine with stock 3.55 gears, though some view them a little low and most actually prefer 4.10. You won't have any issues however.


Red_01_XJ, 4.56 would be WAY to high for 31s..

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I know but I might be moving to 32-33s eventaully

31s and 3.55 sucks IMO.

I have it and am looking to go deeper soon.

I can barely stand it on the street, I can't imagine towing 1500 lbs. with it.

You can tow with it but it will be very slow and if you dont have an auxillary cooler on the tranny it will cook FAST!!! The embarassment of the white smoke bilowing from the vent tube will be bad also.

If you change to 4:10 then you can also upgrade to 33's without much trouble. Just remember how expensive it will all get, Trac bars, long arms, lockers, etc. Definately look at the long term use of the vehicle and what you expect it to do for you.

More feedback:

Mine is a 98 4.0/AW4, with 3.55s and 31" BFG-ATs.

Around town, its fine. Its a touch sluggish feeling right off the line(well, I've' had two other stock XJs, so a little sluggish in comparison, anyway).

Once driving, it doesn't feel bad at all. Does shift a bit more than I'd like on inclines when I'm loping around 55-60 mph or so.

I just did some decent snow wheeling with it. When the snow was 12+" deep, there were times that was straining a bit to rev up/spin the tires. Downshifting a gear took care of things..

Towing, I tow occasionaly with it, utility trailer type towing.

Towing my Flatfender (Stock 53 CJ-3a, so about 2100 lbs) wasn't an issue, seemed just fine for acceleration. Once towing with a tow bar, the other time with a heavy U-haul tow dolly. I could feel the extra weight of the dolly. Braking was a bigger concern than acceleration, for sure.

Towing the utility trailer is no probably, loads up to maybe 2000lbs.

Overall, I would like to go to 4.10s as well. The AW4 has such a nice deep overdrive, I see no reason not to. Its roughly the same RPMs as the AX-15 with 3.73 gears.

I'd probably swap out my 8.25 for a Ford 8.8 with factory 4.10s and then just regear the front. Probably could end up with the stronge raxle and disc brakes, and a factory LSD for roughly the same price as buying and installing gears.

helix said:

Red_01_XJ, 4.56 would be WAY to high for 31s..

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No they wouldn't!

Okay, this is some good info. I have already planned on the tranny cooler as I firmly believe in keeping that cool. I only get out once a month or so, so most of the driving will be without the trailer. It's not a DD so that is not a big concern. Sound like not regearing right away will work until I get the funds to regear. Most likely will only tow a half dozon times with the 3.55's. I am not going any bigger then 31's since my buddy has this setup and goes any place I would ever want to go and even some I don't want to. LOL I think all I need it SYE, driveshaft and tires, though I am going to do the lift with the tires on there now. Might look a little funny but hey, it's a start.

Thanks!

I have no issues with 31's and 3.55's. I didnt notice much lose of power or driveability....

seems everyone feels different about it or has different experiences.

I also have 31 BFG AT's with 4 liter, auto trans, and 3.55 gears.

Going over bigger hills with cruise will cause trans to down shift, less often when going 70+ MPH.

I've towed my pop up camper on several 300 mile trips, no problem, used OD sparingly.

I don't mind my 31's 3.55/AW4 around town but on a recent glacier trip with 3 guys and our climbing/skiing/mountianeering gear it was not pretty. That is running Euro 95 fuel (around 91 in the states). Rolling 3 doing 60 mph = gas guzzler. I have a K & N cone filter and dynomax exhaust. IMO......

31's with 3.55's are A-okay : ) i have 33's with 3.55's but im gettin 4.56's asap...

4" lift 31 MTs and stock 3.55s with a AT.
Flat towed my YJ through Nebraska at 75. Seemed a bit sluggish off the line though
,Ron