Tire size; to regear or not to

In my opinion unless you plan to run much larger wheels like 33" I wouldn't regear your axles.
Regearing the axles is usually a simple job however the Liberty's front axle is IFS.
You will have to drop it to change the gears.

I'm running a 2.5" spacer lift with LT245/75R16 AT tires with my stock gears.
Because I have an automatic transmission I've had the engine computer programmed for the bigger tires so the transmission will shift properly.


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LibertyFever said:

In my opinion unless you plan to run much larger wheels like 33" I wouldn't regear your axles.
Regearing the axles is usually a simple job however the Liberty's front axle is IFS.
You will have to drop it to change the gears.

I'm running a 2.5" spacer lift with LT245/75R16 AT tires with my stock gears.
Because I have an automatic transmission I've had the engine computer programmed for the bigger tires so the transmission will shift properly.


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Front is no big deal to swap,2 hours total at most
Programming the computer is only 50 % of the job, regearing does the rest
Even with 30-31 I have found GREAT benefits to a regear, more power, better mileage , doesn't shift as much since +has more power
33s ? then you're looking at at least 4.56s and steel front diff and 6 inches of lift so yes that goes with out even discussing .

tommudd said:

Front is no big deal to swap,2 hours total at most

Programming the computer is only 50 % of the job, regearing does the rest

Even with 30-31 I have found GREAT benefits to a regear, more power, better mileage , doesn't shift as much since +has more power

33s ? then you're looking at at least 4.56s and steel front diff and 6 inches of lift so yes that goes with out even discussing .

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Thanks for your input Tom.
I must confess that you know far more than I do about Liberty's.

I have done more mods to my 95 YJ than to my Liberty.
It runs on 33" or 35" tires and yes regearing the axles was definitely worth the labour & cost.

Would you agree Tom that once you increase the tire size you put more strain on the axles and u-joints?


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tjkj2002 said:

Get above 5000' elevation and you will change your tune pretty quick.

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At that elevation I'm doing 70mph usually.... downshifting is easy. You and I debate axle ratio often. Really depends on how you use your ride. 3.55 or 3.73 is way snappier than 2.79 in an 80's Dodge half-ton. I also have a cummins Dodge for towing/hauling chores.

tommudd said:

Front is no big deal to swap,2 hours total at most

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Maybe for you. My DIY'er time on my back in the driveway was a half day to take it out; a couple days to change bearings, seals, intermediate shaft; and a half day to re-install. It was spread out some... the Jeep had be be driven in between.

LibertyFever said:

Would you agree that once you increase the tire size you put more strain on the axles and u-joints?

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Based on parts I've used up completely while running bigger tires on the KJ...
- front wheel bearings
- rear ujoint (pinion end)

u2slow said:

At that elevation I'm doing 70mph usually.... downshifting is easy. You and I debate axle ratio often. Really depends on how you use your ride. 3.55 or 3.73 is way snappier than 2.79 in an 80's Dodge half-ton. I also have a cummins Dodge for towing/hauling chores.

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Between 6500' and 8000' before the SFA swap with 265/75R16's and 4.10's doing 80mph was nothing with zero downshifting and over 20mpg's.

Same size tires,1000lbs less weight,and 3.73 gears at sea level to 500' it would shift all the time and got maybe 14mpg's at 65mph.

The day I installed the 265-75-16s I took off on a 300 mile trip
Half way there was ready to turn around and buy a smaller set ( even though I had the rear gears and another front 4.10 diff waiting to go in )
BUT I hated to even drive it all it did was shift back and forth, best I got was about 15 mpg. Finally resigned to the fact that needed to run with OD off
Week later gears installed HUGE SMILE!!!!!!!!!!!!!!!!!!
back to 21 or so on the road and no more shifting all the time

Oh... I'm supposed to get the computer reprogrammed? I have 4:10s and 31s but didn't get anything done too the computer.. Oops

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libordemise said:

Oh... I'm supposed to get the computer reprogrammed? I have 4:10s and 31s but didn't get anything done too the computer.. Oops

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Earlier models you could do a pinion reset on them for the larger tires

tjkj2002 said:

Between 6500' and 8000' before the SFA swap with 265/75R16's and 4.10's doing 80mph was nothing with zero downshifting and over 20mpg's.

Same size tires,1000lbs less weight,and 3.73 gears at sea level to 500' it would shift all the time and got maybe 14mpg's at 65mph.

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I'm starting to understand now... the auto's coarse ratio steppings don't maintain the powerband well when you deplete the effective axle ratio.

Top gears on the 45RFE are 1.50, 1.00, 0.75... and the NSG370 are 1.25, 1.00, 0.84

tommudd said:

Earlier models you could do a pinion reset on them for the larger tires

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No option for that for 05s? Even if I did the programming until getting the 4.10s it'd be a hell of a lot better than it is now

What years is the pinion reset available for?

kejobe said:

What years is the pinion reset available for?

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02-04 for sure, but 05 as well I'm pretty sure , not after that though

Maybe I'll give it a check and take a trip to the dealer next time I think about it..