Regear question

JeepNCrowd · **Posted:** Thu Apr 17, 2014 4:00 pm

tjkj2002 wrote:

JeepNCrowd wrote:

Perhaps the 235/85/R16 will be a friendlier 32 to go with. I know I should still re-gear with them, and if I wasn't planning on replacing the diffs in a couple of years I would, but I'd imagine it wouldn't be as bad as the 265's. It's a lighter tire with less rolling resistance. Again I know re-gearing is recommended, but how much do you better do y'all think the 235's are vs 265's on stock gearing?

235/85's are maybe a few lbs lighter then a 265/75 but the 235/85 is actually slightly taller then a 265/75.Either tire will cause the same power robbing effect.

I used specs for a MT/R K..............

235/85 = 50lbs and is 32" tall on a 6.5" rim

265/75 = 52lbs and is 31.9" tall on a 7.5" rim

I know they're taller that's why I'd go with them instead of 265's. Plus I'm of the belief that narrower is better for most off road situations. Aside from weight I was getting at the 235's less road contact area and thus less rolling resistance. I would think on long highway trips it be better (MPG wise), but a dog around town.

tjkj2002 · **Posted:** Thu Apr 17, 2014 4:07 pm

1" tread width difference is not going to make much difference.

tommudd · **Posted:** Thu Apr 17, 2014 4:32 pm

You would be hard pressed to notice the difference between a set of 235-85-16s and 265-75-16s on the road, no matter in town or out on the highway. Dog either way

Ted15 · **Posted:** Sun Apr 20, 2014 12:16 pm

I tow a rather large pop up camper with my KK. The engine would actually dog so bad that it would ping. (245/75-16) now with Detroit Trutracs in both axles and 4.10 gears I haven't had an issue with power. It actually runs a little better than it did new. I still get crappy mileage but there is a lot of added weight and wind resistance.

Shannon · **Joined:** Sun Jan 20, 2013 6:26 am **Posts:** 60

I regeared to 4.10 when I installed the TM Econolift and am still running stock sized tires...I lost about 2mpg when I thought (hoped) I would gain a couple. Of course, 90% of my driving is hwy at about 60-65mpg. It could be the gas as well...I have a sneaking suspicion that the gas on post is not that great and might be the cause for my intermittent check engine light p0305.

tommudd · **Posted:** Sun Apr 20, 2014 10:10 pm

Shannon wrote:

I regeared to 4.10 when I installed the TM Econolift and am still running stock sized tires...I lost about 2mpg when I thought (hoped) I would gain a couple. Of course, 90% of my driving is hwy at about 60-65mpg. It could be the gas as well...I have a sneaking suspicion that the gas on post is not that great and might be the cause for my intermittent check engine light p0305.

Still running stock size tires as well , will do better when you go to like 245-75-16s

Bmxer524 · **Posted:** Sun Apr 20, 2014 11:48 pm

Shannon wrote:

I regeared to 4.10 when I installed the TM Econolift and am still running stock sized tires...I lost about 2mpg when I thought (hoped) I would gain a couple. Of course, 90% of my driving is hwy at about 60-65mpg. It could be the gas as well...I have a sneaking suspicion that the gas on post is not that great and might be the cause for my intermittent check engine light p0305.

Like Tom said, when you up the tire size a bit, you should gain. Probably feel like a rocket right now lol.

Yeti · **Posted:** Tue Aug 05, 2014 2:49 pm

Guys I have an automatic transmission and I have a question for you , if I regear to 4.10 , I need to programming the TCM or somthing else ?

thanks for any suggestion

Ted15 · **Posted:** Tue Aug 05, 2014 3:23 pm

Yeti wrote:

Guys I have an automatic transmission and I have a question for you , if I regear to 4.10 , I need to programming the TCM or somthing else ?

thanks for any suggestion

Nope, plug and play.

Yeti · **Posted:** Tue Aug 05, 2014 4:09 pm

great , thank you so much Ted :wink:

Ted15 · **Posted:** Tue Aug 05, 2014 4:28 pm

Yeti wrote:

great , thank you so much Ted :wink:

No problem :-)

Yeti · **Posted:** Wed Aug 06, 2014 1:52 pm

sorry , another question , if I put the 4.10 and the 245/75 , I need to reprogram the new tire size ?

thanks a lot

Ted15 · **Posted:** Wed Aug 06, 2014 1:56 pm

Yeti wrote:

sorry , another question , if I put the 4.10 and the 245/75 , I need to reprogram the new tire size ?

thanks a lot

They should cancel each other out unless it's somehow reading the wheel speed.

Yeti · **Posted:** Wed Aug 06, 2014 2:50 pm

JeepMorrison · **Joined:** Thu Jul 16, 2009 11:34 am **Posts:** 1236

So I have made some trips with 3.73 and 32s. At 65 (gps) im running 1900 rpm. Hand calculated 15-16 mpg. Its not very fast, and i have no hills where I live at sea level. If you have hills or at higher altitude then regear.

I cant justify regearing to the boss lady. Especially when some guys I ride with get 14-15 with 245/75s. I want to regear, I know it will change the jeep, but its expensive.

Side note: my tranny and engine temps are the same as 245/75. But again im on flat ground at sea level.

We have one bridge (toll bridge) and my jeep hates it. If I had that the whole drive, id hate the jeep.

Sent with the power of children's screams!!!

tommudd · **Posted:** Thu Aug 07, 2014 11:17 am

4x4kayak2112 wrote:

So I have made some trips with 3.73 and 32s. At 65 (gps) im running 1900 rpm. Hand calculated 15-16 mpg. Its not very fast, and i have no hills where I live at sea level. If you have hills or at higher altitude then regear.

I cant justify regearing to the boss lady. Especially when some guys I ride with get 14-15 with 245/75s. I want to regear, I know it will change the jeep, but its expensive.

Side note: my tranny and engine temps are the same as 245/75. But again im on flat ground at sea level.

We have one bridge (toll bridge) and my jeep hates it. If I had that the whole drive, id hate the jeep.

Sent with the power of children's screams!!!

Northwest Ohio where I did live is pretty flat thanks to the ice age
I couldn't run at 55-60 and not have mine shifting back and forth at least ten times every mile. Had to drive with the OD off all the time. At 80 it would finally have enough to keep going and not shift unless there was a small hill then of course it would start shifting back and forth. I hated my KJ the whole couple of weeks I had to wait to regear.

tjkj2002 · **Posted:** Thu Aug 07, 2014 11:23 am

tommudd wrote:

4x4kayak2112 wrote:

So I have made some trips with 3.73 and 32s. At 65 (gps) im running 1900 rpm. Hand calculated 15-16 mpg. Its not very fast, and i have no hills where I live at sea level. If you have hills or at higher altitude then regear.

I cant justify regearing to the boss lady. Especially when some guys I ride with get 14-15 with 245/75s. I want to regear, I know it will change the jeep, but its expensive.

Side note: my tranny and engine temps are the same as 245/75. But again im on flat ground at sea level.

We have one bridge (toll bridge) and my jeep hates it. If I had that the whole drive, id hate the jeep.

Sent with the power of children's screams!!!

Northwest Ohio where I did live is pretty flat thanks to the ice age
I couldn't run at 55-60 and not have mine shifting back and forth at least ten times every mile. Had to drive with the OD off all the time. At 80 it would finally have enough to keep going and not shift unless there was a small hill then of course it would start shifting back and forth. I hated my KJ the whole couple of weeks I had to wait to regear.

Try living in Colorado!!!!!

With 5.13's my KJ is still a little sluggish but when I go home to South Dakota(5000' less elevation and flat,east side of state) my KJ feels like a Ferrari,the slightest tap on the stupid pedal and I brake those rear 35" tires loose.Put's a ear to ear grin on the face till you got to buy new tires.

JeepMorrison · **Joined:** Thu Jul 16, 2009 11:34 am **Posts:** 1236

I drove it to the hill country of Texas last week, it did what tom said, shifted all crazy and slowed way down going up hill. But I dont ever drive up there very often (had to grab my trailer from sisters house). But home town driving it runs fine and stays in the right gear. Maybe its the 06 tranny, and different gearing in it.

We usally take the wifes Grand if we go anywhere farther than into houston (40 miles). The KJ is just so much rougher and louder, and her seats in the Grand are soooo nice.

Sent with the power of children's screams!!!

Yeti · **Posted:** Thu Aug 07, 2014 12:45 pm

I drive only on mountain roads then regear is needed, what I wanted to know is if changing tire size and gear ratio, it was necessary to re-calibrate the speedometer or the abs

thank you

JeepMorrison · **Joined:** Thu Jul 16, 2009 11:34 am **Posts:** 1236

My speedometer is off 2mph at 60 mph. And the abs will be fine.

Drop gears/tirea in and go.

Sent with the power of children's screams!!!

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