Tire size; to regear or not to

[SinewStew]

I recently ordered a full OME lift and Jeepinbyal A-arms. I drive on the beach a lot and some back trails in the southern Appalachian mountains. As far as I'm aware, the only gearing options available for the gasoline versions are 3.73 for the 3.7 or 4.10 for the 2.4. I want to go up to a 30" tire. According to the chart on this page: GEAR CHANGE & TIRE SIZE CHART 30" is at the bottom end of the ideal power band. According to their formula to go from a 29" to a 30" would require a gearing ratio of 3.84 to match the stock ratio. That's closer to 3.73 than 4.10. Based on that information, would you say a 30" off-road tire would be best compatible with 3.73 option already installed on my 3.7 gasoline Jeep Liberty?

 

[tommudd]

I recently ordered a full OME lift and Jeepinbyal A-arms. I drive on the beach a lot and some back trails in the southern Appalachian mountains. As far as I'm aware, the only gearing options available for the gasoline versions are 3.73 for the 3.7 or 4.10 for the 2.4. I want to go up to a 30" tire. According to the chart on this page: GEAR CHANGE & TIRE SIZE CHART 30" is at the bottom end of the ideal power band. According to their formula to go from a 29" to a 30" would require a gearing ratio of 3.84 to match the stock ratio. That's closer to 3.73 than 4.10. Based on that information, would you say a 30" off-road tire would be best compatible with 3.73 option already installed on my 3.7 gasoline Jeep Liberty?

What size are you actually wanting to run?
What OME kit did you get ( springs rate wise ) ?
There are more options depending on if automatic or manual transmission.
BUT as far as some of those charts I take them with a grain of salt , its a formula not exact science and doesn't take into count the exact vehicle.
With that said when you lift a vehicle , add taller and heavier tires, possibly heavier wheels etc you need to figure all of that into the final result
So, I'm running 265-70-16s ( 30.7 inches tall ) on my 03 currently, with 2.5 inch JBA coilover lift. Also running 4.10s which do great all around .
On my 04, Ran 265-75-16s ( 32s ) with 4.10s and over 4 inches of lift, but it was never quite enough in Southeastern Ohios hills or any where South or East, hook on a trailer and even worse.
My wife is in Winston Salem lecturing ( did last year as well ) so I have been running up and down I-70 through WVa/ Va and Norther NC, and of course up and down Fancy gap, quite a bit.
Coming up Fancy Gap I have no problems hitting the bottom at 70 and topping over at 75 or so. I'm sure you know how that little hill can be.
SO............my vote is always and will always be to regear, keeps the motor in the power band, transmission is happier and not hunting for the right gear.
We've also done 3 other KJs here at my place switch to 4.10s TwoBobs was running 265-70-16s as well , and John was running 245-75-16s when we did his 4.10s. The other one I lifted and did 3 inch lift and 245-75-16s on hers and her and her husband both loved the power and mileage

 

[profdlp]

...My wife is in Winston Salem lecturing...

You're lucky. Most wives do that right in their own home. :Violin:

 

[sparky123321]

Running 30x9.5-15's with no regearing and no problems.

 

[tommudd]

Running 30x9.5-15's with no regearing and no problems.

Considering stock tires are 29 inches tall and 30-9.50-15s are 29.5 , not much difference at all, same as using 245-70-16s
But since the OP didn't really tell what size he is going to run , we're still guessing
With that said one guy we lifted here had 4.10s installed with lockers and ran that way for quite a while till we lifted it , loved the power

 

[tommudd]

You're lucky. Most wives do that right in their own home. :Violin:

She does it by text now............................................:emotions34:

 

[renegade 04]

I just completed a regear to 4.10's and I have 245/70R16. even with stock size tires you will see a big difference when you upgrade to 4.10's. During the regear I also upgraded to a True Trac rear carrier and a Eaton electronic locker up front.

 

[SinewStew]

Considering stock tires are 29 inches tall and 30-9.50-15s are 29.5 , not much difference at all, same as using 245-70-16s
But since the OP didn't really tell what size he is going to run , we're still guessing
With that said one guy we lifted here had 4.10s installed with lockers and ran that way for quite a while till we lifted it , loved the power

I really don't know what size I want to run. I purchased an OME 1.5 kit from Jeepinbyal, HD rated springs and A-Arms. I just dropped a bunch of cash on the kit and I'm not interested in spending $1000 to regear. I'm using my funds to build a cabin in Pisgah forest, which is part of the reason I need the upgrade. Getting there is rough country. I can't afford to do both. So I suppose a better question would be, what's the largest tire that would be best with the original gearing and that lift?

 

[tommudd]

I really don't know what size I want to run. I purchased an OME 1.5 kit from Jeepinbyal, HD rated springs and A-Arms. I just dropped a bunch of cash on the kit and I'm not interested in spending $1000 to regear. I'm using my funds to build a cabin in Pisgah forest, which is part of the reason I need the upgrade. Getting there is rough country. I can't afford to do both. So I suppose a better question would be, what's the largest tire that would be best with the original gearing and that lift?

Well if you got the 927/948 springs then you have 2.5 inches of lift not 1.5 inches 9 1.5 is advertised height due to regs down under )
Look around JYs etc for a 4 cylinder KJ, they had 4.10s grab both front and rear diffs and be done

If you can not find any then we are right back to what I posted above. You can run a 30-30.5 inch tire BUT expect to lose some power and mileage . Taller you go over 29 inches the more you lose
Some try and run 32s with stock gearing but it suc*s trying to drive it, forget about using over drive, motor runs hotter, transmission is always looking for the right gear .
So 245-70-16s or 245-75-16s ............

 

[kejobe]

As stated, regearing is best, but for an example, I have 265/70/16's with the stock 3.73 gears. Is it optimal? No. Is it recommended? Absolutely not. Can it be done? Yes. I've been running the 265's for about a year now with no dire consequences. Granted it's only been 4000ish miles, but it can be done until the funds are there for gears.

During that time I was traveling 50 miles round trip for work. Now it's down to about 1.5 miles round trip so I'm not as worried about regearing as it's a toy/winter vehicle. Even as a DD, at 1.5 miles, I still wouldn't be worried.

This is just my opinion and you know what they say about those.

 

[tommudd]

As stated, regearing is best, but for an example, I have 265/70/16's with the stock 3.73 gears. Is it optimal? No. Is it recommended? Absolutely not. Can it be done? Yes. I've been running the 265's for about a year now with no dire consequences. Granted it's only been 4000ish miles, but it can be done until the funds are there for gears.

During that time I was traveling 50 miles round trip for work. Now it's down to about 1.5 miles round trip so I'm not as worried about regearing as it's a toy/winter vehicle. Even as a DD, at 1.5 miles, I still wouldn't be worried.

This is just my opinion and you know what they say about those.

Little difference, I have trailers hooked onto mine and travel very hilly country more in 3 months than you drive in a year.
But still wouldn't with out a regear SO much fun playing with others at stop lights even :happy175:

 

[u2slow]

Still running stock 3.55 gears. 245/75R16 tires went on in 2012. Hasn't been a problem for how we use the Jeep.

I have used 3.73s sitting on my bench. No real drive to put them in until a diff wears out or dies.

 

[Cardhu]

The low end of 3rd in mine was a miserable ratio in 50 km /h zones. If i kept it it would have been 4.56's next.

 

[tommudd]

Still running stock 3.55 gears. 245/75R16 tires went on in 2012. Hasn't been a problem for how we use the Jeep.

I have used 3.73s sitting on my bench. No real drive to put them in until a diff wears out or dies.

WOULDN'T EVEN MESS WITH GOING FROM 3.55 TO 3.73s GO TO 4.10s
good friend went larger tires on his 5 speed, said it did fine, finally went to 4.10s and called me screaming " Its like driving it when it was brand new with stock size tires!!! WHY did you make me wait so long LOL "

 

[u2slow]

WOULDN'T EVEN MESS WITH GOING FROM 3.55 TO 3.73s GO TO 4.10s
good friend went larger tires on his 5 speed, said it did fine, finally went to 4.10s and called me screaming " Its like driving it when it was brand new with stock size tires!!! WHY did you make me wait so long LOL "

Sounds good for racing between traffic lights (none of those here).

All 6 gears get used and nothing feels lacking... so messing with ratios is just a make-work project IMO.

Besides, 4.10 is something I have to go pay retail price for. Used 3.73's nearly fell in my lap.

 

[tommudd]

Sounds good for racing between traffic lights (none of those here).

All 6 gears get used and nothing feels lacking... so messing with ratios is just a make-work project IMO.

Besides, 4.10 is something I have to go pay retail price for. Used 3.73's nearly fell in my lap.

Good for hills/ keeping speed at highway speeds / more power at all times
regearing is the single best things besides an upgraded suspension you can do to a KJ/KK
Everything else is just fluff , ( before LEDs , huge loud music machines, fancy wheels, chrome stuff etc LOL)

 

[tjkj2002]

Sounds good for racing between traffic lights (none of those here).

All 6 gears get used and nothing feels lacking... so messing with ratios is just a make-work project IMO.

Besides, 4.10 is something I have to go pay retail price for. Used 3.73's nearly fell in my lap.

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

 

[jeeplib05]

What is the typical pricing on getting 4.10s? Really want my KJ done since I drive it in the winter but don't really want to spend a lot on it
Badly needed for my 31s though ..

 

[tommudd]

What is the typical pricing on getting 4.10s? Really want my KJ done since I drive it in the winter but don't really want to spend a lot on it
Badly needed for my 31s though ..

Shop around for a 4 cylinder , The set I'm running riight now I bought 4 -5 miles from me at a junk yard, under 60,000. Did have to pay 500 for the pair.
But then a buddy saw a KJ sitting in a backyard down home and stopped talked to the owner . Was going to junk it due to motor and transmission being bad . He called me saying "you more than likely don't want this one but its 300 bucks because its a 4 cylinder! " So pulled the front and diffs, for less than 300 . Now spare set. So they are out there
But all new, depends on labor prices but 1200-1500 is an average

 

[wheeee32]

$1200 for everything on mine after parts and labor. 4:10's are still the best mod I've done right after the lift. My last road trip up to Shenandoah was proof positive as I easily rolled away from a group of Wranglers that had gone bigger tires/lift without regearing. I found that out later on when they caught up to me at a pull-off area to take pictures and asked me my mods.:gr_grin: