31's with 3.55's?

[94CountryXJ]

Youll like yourself better(later) if you 4.56's!

How does 4.56's with 33's and a AW4 work on the highway? Also what about with 31's?

 

[Archdukeferdinand]

All I can tell you is that those are the numbers I was getting in mixed driving. Measurements were taken from the overhead console after installing the correct speedo gear in the transfer case; this was in turn double-checked against my GPS unit and fuel receipts for accuracy. The amount of variation between the two was virtually zero.

If you were getting better fuel economy in your particular circumstances, I'm thrilled for you - but your circumstances don't necessarily match mine. Also, how were you determining your fuel economy? Was your speedo corrected after your lift? What year is the XJ you were taking the measurements on? All of these things (and more) affect the overall numbers.



Perhaps not in your specific case, but that seems to be the exception rather than the norm.

I get about 15 mpg out of my 33x12.50s w3.55s and AW4 in a '97 mileage calculated by simple multiplication, figures verified by radar and known amounts of fuel consumed over known distances traveled.

This being said, 33s on 3.55s SUCKS, the tranny is always searching for gears... I plan on going 4.88s and 35s shortly

Edit: To be somewhat on topic, I drove on 31s for a couple of years. Barely noticed it with all terrains, noticed it a good deal with heavy mud terrains.

 

[ILLXJ]

How does 4.56's with 33's and a AW4 work on the highway? Also what about with 31's?

4.56's are what you want with that combo. I got 18-19 with 31's, dropped down to around 16 with 33's. That is highway mileage, little less in mixed driving. 4.10's will be alittle lower. JIM.

 

[RCP Phx]

How does 4.56's with 33's and a AW4 work on the highway? Also what about with 31's?

Ive been running 4.10's in my 2K for 8 years now with 33's and 32's.Ive got 4.56's in my 95 w/ 33's.I use the 2000 for all my road trips and it isnt bad if lightly loaded(and the 32's),but I wished I had 4.56's in it!

 

[3XJFamily]

How does 4.56's with 33's and a AW4 work on the highway? Also what about with 31's?

I'm running 4.56 with 31's now until I go to 32/33 inch tires. I'm comfortable running up to about 70. I thought 31's and 3.55's were OK until I regeared and found out how bad they sucked. Fresh 4.0, header. exhaust, injectors - not a tired engine issue. My daily drive requires me to cross a 4-lane highway of heavy traffic, and accelerate to 60+ coming up a long grade - NOT a comfortable task when I had 3.55's. . . No issue now.

 

[markw]

Anything other than stock sized tires with stock gears sucks. Yes, you will survive, yes it "will work" but performance drops off dramatically, and your mileage will drop. For those with 3.55's and 31's or 33's, you will smack yourself when/if you ever regear, it will be like a new Jeep. Also, when running the bigger tires, consider a nice tranny cooler, if you're running 3.55's and tall tires, how's your fluid look?

Here's the ratios you should run for given tire size:

31's 4.10's
33's 4.56's
35's 4.88's

 

[grimah1w]

Thanks Mark!
I do not like 31s with 3.55...have to keep dropping out of o/d to find pep to do any real acceleration

 

[markw]

Thanks Mark!
I do not like 31s with 3.55...have to keep dropping out of o/d to find pep to do any real acceleration

If you don't plan on larger than 31's, then 4.10's work great, and you can find 4.10 front D30's out of 4cyl XJ's. Generally you can walk out of the Pick A Parts with one of those for < 150 here in socal. If you plan on taller tires than 31's, just go straight to 4.56's.

 

[01MonsterXJ]

I would strongly recommend 4.56's if you ever decide you may want to go to 33's. To get a ratio that would be perfect match to what the ratio is from the factory with stock tires and 3.55's you would technically want to run a 4.33. But I dont think they make those for our jeeps so 4.56's are the closest you can get. I am running 33's with 3.55's and I get like 11-12 mpg mixed driving. 4.56's are next on the list!

 

[winkosmosis]

Anything other than stock sized tires with stock gears sucks. Yes, you will survive, yes it "will work" but performance drops off dramatically, and your mileage will drop. For those with 3.55's and 31's or 33's, you will smack yourself when/if you ever regear, it will be like a new Jeep. Also, when running the bigger tires, consider a nice tranny cooler, if you're running 3.55's and tall tires, how's your fluid look?

Here's the ratios you should run for given tire size:

31's 4.10's
33's 4.56's
35's 4.88's

You people need to stop with the exaggerating. My 31" are fine with stock gears. I have plenty of power and gas mileage improved a little.

 

[techno1154]

You people need to stop with the exaggerating. My 31" are fine with stock gears. I have plenty of power and gas mileage improved a little.

Doing 0 to 60 MPH in 6 miles with a very lightly loaded XJ on flat road on low altitude like Houston may be good to many. Anything else is simply not acceptable to most drivers. 500 to 600 pounds of gear, 30" tires and 3.55 gears on mountainous region is bad. Every time I fill the tank with gas, the performanance deterirates even more. Having the AW4 gear hunt on every incline frustrates me every time. Shifting to 3rd gear, 3,000+ RPM you watch the gas guage go down as the XJ go up the hill :tear:. Is it drivable? Yes it is. Is it satisfactory? It is your call.

I now have 4.10 gears and it is the best thing I have done to my XJ since tossing the mechanical fan 4 years ago. party1:

 

[94CountryXJ]

So looks like I'm going with 4.56's. They may be a lil much for my 31's at the moment. But, when I do step up to 33's I'll be set. I have a line on a 8.8 so may hold off until that goes in as well.

 

[macs97XJ]

I know on my 97 w/manual, after I went to 31's with the factory 3:07 gearing, my power has fell off the table, 3rd & 4th are my favorite gears.

I'm piggy banking for 4:11's, and new carriers.

Jim

 

[vortex]

well this thread made it pretty far so the real test comes this evening as I'm going to the JY to get some grand Cherokee wheels for my new tires! So I'll let you all know how it works out and what i think about it!

thank you all for the input and such...good luck to all and maybe see some locals on the trails!

-PJ-

 

[DeathValleyPaul]

My gas mileage dropped down to about 18 with the 31s. Used to be in the low 20s with the stock tires. It shifts well and runs great with the 31's. When i run 32s, I leave my automatic in 3rd up to 65 mph to keep it from lugging, and the gas mileage sucks down to 15. The 31s are a nice compromise.

 

[MoparManiac]

500 to 600 pounds of gear

:shocked:

Damn what are you packing? Does that include yourself or something?

I Probably only bring like 60-100 lbs worth of stuff unless I was going to go camping. Even then probably only another 100 lbs. 200 lbs more tops.

 

[xjtrailrider]

I have run 32's on 3.55 and it wasn't bad on or off road, my son runs 31's and 3.55's and his 96 still has plenty off pull to it.

In my trail rig I carry 300-400# in the back, tools, spare parts, OBA, spare, etc. I'm ready for whatever I break!

My trail rig is geared 4.10 on 32's and is soon to be 4.88 on 35's

 

[vortex]

Well i got my tires on there and they really do work well they will spin if i need them too....i an very satisfied with the out come of the gear/tire combo!!!

Thanks for all of the input you guys have given me...

-PJ-

 

[89xj]

Well i got my tires on there and they really do work well they will spin if i need them too....i an very satisfied with the out come of the gear/tire combo!!!

Thanks for all of the input you guys have given me...

-PJ-

what gearing and tire combo do you end up going with? 4.10 and 31's???