Do I need to regear if I get 34” tires on my 2 door Sport S

Yondu_JLU

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Stuck between getting 33” tires and 34” tires but I don’t want to have to re-gear...

I have a 2018 JL Sport S auto with a 2.0L turbo engine. If I get 34” tires, do I need to re-gear my Jeep?
IMO, no. I have a JLU Sport S on HEAVY 35" Nitto's and beadlocks with the 2.0 + auto trans, works fine with the 3.45's. Still plenty of get up and go. Like others have said, a Tazer seems like a good investment to correct shift points. Finally calibrating mine after a few months and I'm hopeful that it'll refine that aspect.





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zeebo56

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same here. 35s on auto trans. jeep runs great.
I agree, we both have 35's on our Auto sports, steel bumpers, skid plates and we still get decent get up and go.

However I will possibly be trying 4.88s just to see what the difference may be.
 

DadJokes

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35’s on my sport s. I don’t see 8th gear as much as stock but I still do see it. Usually anything above 72mph I don’t get 8th. Below that I can consistently get it. Still average 19-20 mpg highway and 16-17 city. No problems wheeling it either. I don’t do anything above a blue rated trail though.

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What size is that? Thanks
 

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Get the tires, see how it drives. Especially at highway speeds, passing and merging. Do try it in 4lo too before you make any decision. You'll know if you need new gears.
 

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CarbonSteel

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OK, I will be the guy who disagrees with what most have said. I have a Rubicon with 4.10 gears that came with 33" tires. I recently upgraded to 315/70/17 (35" tires) and yes, it "works" if the definition of works is that you can put it in drive and it will go.

However, 8th gear is rare, headwinds and hills will have you in 6th in the blink of an eye, gas mileage is down, and overall power and driveability are also down and it is due to one thing--the engine is no longer operating in its optimum range and yes, I have a taser mini and changed all of the required settings.

I chose tires which were only 4 pounds heavier than the 33" tires they replaced so the rotating mass is a bit more, but nothing like those going from 31's to 35's.

I am waiting on the master install kits to re-gear mine to 4.88 because I want my Rubicon to have the power levels it had prior to the tire upgrade plus a bit more.

Based upon my experience with 4.10 gears and 35's, I struggle to understand how people say with 3.45 gears and 35's that "everything is ok and it runs fine" so no need to re-gear.
 

zeebo56

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OK, I will be the guy who disagrees with what most have said. I have a Rubicon with 4.10 gears that came with 33" tires. I recently upgraded to 315/70/17 (35" tires) and yes, it "works" if the definition of works is that you can put it in drive and it will go.

However, 8th gear is rare, headwinds and hills will have you in 6th in the blink of an eye, gas mileage is down, and overall power and driveability are also down and it is due to one thing--the engine is no longer operating in its optimum range and yes, I have a taser mini and changed all of the required settings.

I chose tires which were only 4 pounds heavier than the 33" tires they replaced so the rotating mass is a bit more, but nothing like those going from 31's to 35's.

I am waiting on the master install kits to re-gear mine to 4.88 because I want my Rubicon to have the power levels it had prior to the tire upgrade plus a bit more.

Based upon my experience with 4.10 gears and 35's, I struggle to understand how people say with 3.45 gears and 35's that "everything is ok and it runs fine" so no need to re-gear.
I agree with this. I was merely just saying you can get by but yes you are sacrificing several things. Power and gas mileage for sure. But it does still have a little get up and go.

With that said I will be attempting installing to 4.88s this weekend since I would like to get some power back.
 

DadJokes

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OK, I will be the guy who disagrees with what most have said. I have a Rubicon with 4.10 gears that came with 33" tires. I recently upgraded to 315/70/17 (35" tires) and yes, it "works" if the definition of works is that you can put it in drive and it will go.

However, 8th gear is rare, headwinds and hills will have you in 6th in the blink of an eye, gas mileage is down, and overall power and driveability are also down and it is due to one thing--the engine is no longer operating in its optimum range and yes, I have a taser mini and changed all of the required settings.

I chose tires which were only 4 pounds heavier than the 33" tires they replaced so the rotating mass is a bit more, but nothing like those going from 31's to 35's.

I am waiting on the master install kits to re-gear mine to 4.88 because I want my Rubicon to have the power levels it had prior to the tire upgrade plus a bit more.

Based upon my experience with 4.10 gears and 35's, I struggle to understand how people say with 3.45 gears and 35's that "everything is ok and it runs fine" so no need to re-gear.
Thanks for the feedback. What engine?

Right now, with stock 32’s, it seems it doesn’t take much to lose 8th gear. I’ll probably do a gear swap next winter and just get everything else we need for our plans this year.
 
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CarbonSteel

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Thanks for the feedback. What engine?

Right now, with stock 32’s, it seems it doesn’t take much to lose 8th gear. I’ll probably do a gear swap next winter and just get everything else we need for our plans this year.
I have the 3.6L and truth be told, the stock 33's and 4.10 were not optimal either because it would behave in a similar fashion in headwinds, hills, etc, though not quite as bad as it does with the 35's.

I once posted on here that 4.56 should be the stock gear for Rubicon's with 33's and got flamed for it with responses of "must be a new owner" or "that's normal". It's only normal because it has been accepted to be that and not because it should be.

Based upon my experience, if you have 3.45 gears, regearing will give you back the Jeep experience you want.
 

Yondu_JLU

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OK, I will be the guy who disagrees with what most have said. I have a Rubicon with 4.10 gears that came with 33" tires. I recently upgraded to 315/70/17 (35" tires) and yes, it "works" if the definition of works is that you can put it in drive and it will go.

However, 8th gear is rare, headwinds and hills will have you in 6th in the blink of an eye, gas mileage is down, and overall power and driveability are also down and it is due to one thing--the engine is no longer operating in its optimum range and yes, I have a taser mini and changed all of the required settings.

I chose tires which were only 4 pounds heavier than the 33" tires they replaced so the rotating mass is a bit more, but nothing like those going from 31's to 35's.

I am waiting on the master install kits to re-gear mine to 4.88 because I want my Rubicon to have the power levels it had prior to the tire upgrade plus a bit more.

Based upon my experience with 4.10 gears and 35's, I struggle to understand how people say with 3.45 gears and 35's that "everything is ok and it runs fine" so no need to re-gear.
Never said it was IDEAL, but it gets up and goes decently well all things considered. I only occasionally see 8th on the highway and gas mileage has certainly taken a toll, but it's livable. Plenty of people are running Rubi's with 4.10's on 37's and 38's and haven't had an issue....so maybe it's just personal preference.
 

CarbonSteel

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Never said it was IDEAL, but it gets up and goes decently well all things considered. I only occasionally see 8th on the highway and gas mileage has certainly taken a toll, but it's livable. Plenty of people are running Rubi's with 4.10's on 37's and 38's and haven't had an issue....so maybe it's just personal preference.
I am not calling you or anyone out in particular, this is a general statement that is often made when someone asks "should I re-gear". For those running 4.10's and 37's and 38's that have not had an issue, that would have to be defined. I will step in it again and say those folks are "living with it", but given the choice they would re-gear without hesitation.

My Rubicon is not broken and there are no operational issues, but it is not working as it should be. The engine is not in its proper RPM range and it shows in a number of ways--power, MPG, drivability, etc. So yes, it goes, but is it optimum or even close to optimal ? No way...
 

Yondu_JLU

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I am not calling you or anyone out in particular, this is a general statement that is often made when someone asks "should I re-gear". For those running 4.10's and 37's and 38's that have not had an issue, that would have to be defined. I will step in it again and say those folks are "living with it", but given the choice they would re-gear without hesitation.

My Rubicon is not broken and there are no operational issues, but it is not working as it should be. The engine is not in its proper RPM range and it shows in a number of ways--power, MPG, drivability, etc. So yes, it goes, but is it optimum or even close to optimal ? No way...
Based on your response, I think we both have a similar outlook. In the end, yes, I agree it is not optimal for some uses. But I think it is reasonable to argue that one should experience the stock ratio for themselves before jumping the gun and re-gearing.
 

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