Necessary to regear for 33” tires on 3:45 ratio?

[72commando]

i would think the stock axles could handle the 33s. especially if theyre the KO2s which are slightly under 33. the stock Sport tires are 31.5 and Sahara are 32" i believe. (with same axles i believe). id be more concerned with bigger than 33".



which programmer did you go with?

I used a flashcal because i got one super cheap but a tazer would also work. I would look at all the features they each have then decide which one you would use the most. The dealers wanted $125 for a one time program and only one dealer almost 2 hours away had the new system to do it so i did it myself.

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[ryandamartini]

I have a jlu sport s with the auto. Just going to 285 70 tires completely changed the driving dynamic of the vehicle. I’m not happy with it at all right now. It’s ok for puttering around town but on the interstate, 8th gear is gone. I live in flat southern Florida so at sea level too. Best case scenario. It needs gears. Period. You’re going to be SO much happier with it being re geared. I’m deciding between 4.10 and 4.56 for 35s.

 

[codyboyjl]

Absolutely not necessary to regear with 33s. I've only had 33s on my JL with 3.45 and everything is completely fine. I do have aftermarket exhaust and CAI, but it handles and performs just fine with 33s. I've seen my MPG go as high as 18.7 and I do 50/50 highway/city driving. Apparently regearing is always ideal though.

 

[Uhdinator]

2.0l auto Sport HT with 2" spacers and 305/65 (32.5 I think). Was set up this way from the dealer but they did not upgrade the shocks. It does not feel powerless. Runs in 7th gear at 55 1600 rpm, and 8th at 70 1800rpm. I think the Auto prob handles it better than a 6 sp stick. I've been around 25-26 mpg for the last 2 fill-ups with 91 octane. That could be off as the speedo cal is off. They said they calibrated but I told them it was off according to my I phone gps. I haven't tried calibration yet with the RC quickcal they included with the jeep. Oh and I upgraded the shocks with RS5000x rancho's and the ride is better. The bigger tires needed more control of a better shock. This was sitting next to a stock Rubicon and I thought it actually looked better. If a was gonna do a lot of off road wheeling the Sport S with a D44/220 with 3.73 and LSD would be a better choice with big tires. I couldn't do the Rubicon @ 20K more than the first one I bought in 2003.

 

[Yoyo27983]

if calculations serve me right, stock sport has 31” tires- according to most charts ( which may be outdated) that’s already outside optimum performance/ mileage range.

Not something I’d plan on doing immediately anyway, but it’d be good to know if the 3.45 can handle a slightly bigger size without any bizarre side effects

I just went thru this. I also went for the Mopar 2 " lift with 33" 285/70R17 on gear head big block rims. The lift killed my 8th gear and gas mileage. Then I added the tires. I am getting around 15 mpg and rarely see 8th gear anymore. I am considering removing the lift. Good luck!

 

[Yoyo27983]

Update! I carried the Jeep in to have the speedo recalibrated. The dealership kept the Jeep through the weekend. They could not duplicate the rear brake issue but they assumed that it had something to do with resetting the abs system after a bcm update. They told me that the abs usually needs a reset after any other configuration updates. BS ?? I DON'T KNOW. I picked it up Monday afternoon and in the 20 mile ride home it was performing great. It went to 8th gear again and would only occasionally downshift to 7th. The gas milage is now showing 22 at 60mph. At 50mph ,it is around 28mpg. This is very good news to me! Now let's hope nothing else happens with this thing. I still have to carry it to another dealer for a second opinion on the engine knock. Will update that in the thread on 3.6 sound at idle. Thanks to all of you who pushed to get the speedo recal'd.

 

[redsyphon]

Update! I carried the Jeep in to have the speedo recalibrated. The dealership kept the Jeep through the weekend. They could not duplicate the rear brake issue but they assumed that it had something to do with resetting the abs system after a bcm update. They told me that the abs usually needs a reset after any other configuration updates. BS ?? I DON'T KNOW. I picked it up Monday afternoon and in the 20 mile ride home it was performing great. It went to 8th gear again and would only occasionally downshift to 7th. The gas milage is now showing 22 at 60mph. At 50mph ,it is around 28mpg. This is very good news to me! Now let's hope nothing else happens with this thing. I still have to carry it to another dealer for a second opinion on the engine knock. Will update that in the thread on 3.6 sound at idle. Thanks to all of you who pushed to get the speedo recal'd.

I was also told that a re-cal would fix potential ABS issues after changing out my tires. So at least my dealership is consistent with your's in that it does have some crossover with the ABS systems on the JLs.

I can say that (even with the manual) I did notice a difference in power & fuel-economy after they updated the Jeep for the Rubi-Takeoffs. I'm only seeing 22-23 highway at 65-75 with the 6spd manual (3.45 gears), but that's better than the 16mpg it was reporting before the re-cal... the 2.5 lift and LoD bumper + Winch probably aren't helping with mpg either. :P

 

[TrailTorque]

I’ve been running 17x9’s with a 4.75” backspace on 33’s 11.5 wide, no lift, without any issues at all. Tires are Nitto Ridge Grapplers. Would highly recommend.

Old pic:

I would however regear if going to 35’s and up. Just my personal opinion. I have M186/M220. 6Spd M/T

Note: my tires actually measure nearly 34”

 

[dirtygertie_jlu]

Does anyone know if the drop in MPG when upgrading from stock to 33s is as noticeable in the 2.0 turbo as in the V6, which most posts seem to be referencing?

 

[rcpeters]

I have a Sport 2.O and moved up to 33" MT. After setting the calibration I didn't notice much differnce in MPGs.

 

[Vedder]

I’ve been running 17x9’s with a 4.75” backspace on 33’s 11.5 wide, no lift, without any issues at all. Tires are Nitto Ridge Grapplers. Would highly recommend.

Old pic:

I would however regear if going to 35’s and up. Just my personal opinion. I have M186/M220. 6Spd M/T

Note: my tires actually measure nearly 34”

Are these 285/75/17?

 

[KrazyKirk]

I am new to the forum and looking at the comments i have a little to offer and a question. I recently installed 35's (General Grabber 3's) on my 2018 Wrangler Unlimited Sahara. They are on 17" Mamba wheels with a +6 offset which puts the tire only about an 1" passed the fender. There was no rubbing at all when just traveling on the road. the tires are a little louder than stock but for their aggressive tread they are very good noise wise. Doing a couple of articulation test I could see off road issues. I had a BDS 2" lift installed and there are no issues off road. I am going to install a beefier steering stabilizer as on big dips in the road it can push you to one side. The 8 speed automatic works well but will hang in 7th gear even at a decent clip on an upward incline. My problem is the dealer says they cannot reprogram the speedometer to the 3.45 gears. They want $175.00 and cannot do it, they actually said to try another dealer. They sell many new vehicles with 35's on them and the manager tells me they have the new owner sign a waiver that they are aware the speedometer is off. This also throws off the mileage on the odometer and can be a huge headache if one has to sell the vehicle as it will have more miles on it than what it actually shows. As for the speedometer the factory tires were 32's and now at 60 MPH the actual speed is 65 to 66. Does anyone know of a dealer in the area that can do this for me? I near in Middletown, Delaware.

 

[redsyphon]

I am new to the forum and looking at the comments i have a little to offer and a question. I recently installed 35's (General Grabber 3's) on my 2018 Wrangler Unlimited Sahara. They are on 17" Mamba wheels with a +6 offset which puts the tire only about an 1" passed the fender. There was no rubbing at all when just traveling on the road. the tires are a little louder than stock but for their aggressive tread they are very good noise wise. Doing a couple of articulation test I could see off road issues. I had a BDS 2" lift installed and there are no issues off road. I am going to install a beefier steering stabilizer as on big dips in the road it can push you to one side. The 8 speed automatic works well but will hang in 7th gear even at a decent clip on an upward incline. My problem is the dealer says they cannot reprogram the speedometer to the 3.45 gears. They want $175.00 and cannot do it, they actually said to try another dealer. They sell many new vehicles with 35's on them and the manager tells me they have the new owner sign a waiver that they are aware the speedometer is off. This also throws off the mileage on the odometer and can be a huge headache if one has to sell the vehicle as it will have more miles on it than what it actually shows. As for the speedometer the factory tires were 32's and now at 60 MPH the actual speed is 65 to 66. Does anyone know of a dealer in the area that can do this for me? I near in Middletown, Delaware.

Wow!

I'd start using a different dealership if you have another one within a reasonable driving distance. The one described above seems a bit shady.

I would think any Jeep Dealership should have the ability to update and alter the Jeeps computer/programming. I'd just call to the service department of another dealership and ask them if they can re-program your vehicle (give them the vin) for 35in tires.

As a side note, ontop of the speedo readings, the Dealerships here (FL) I checked with all gave me the same speech that it's a slight safety concern on the JLs to not re-program as it can throw the computer off for things like Anti-lock breaking, etc... I'm sure they just want the $$, but with the amount of electronics in the new JL, I figured better safe than sorry.

 

[Jeepjunkie]

I just bought a Tazer. I can adjust my speedometer anytime I want and not worry about the dealer. After 2 reprograms it has paid for itself. And I use the live functions like ESS disable too.

 

[KrazyKirk]

Wow!

I'd start using a different dealership if you have another one within a reasonable driving distance. The one described above seems a bit shady.

I would think any Jeep Dealership should have the ability to update and alter the Jeeps computer/programming. I'd just call to the service department of another dealership and ask them if they can re-program your vehicle (give them the vin) for 35in tires.

As a side note, ontop of the speedo readings, the Dealerships here (FL) I checked with all gave me the same speech that it's a slight safety concern on the JLs to not re-program as it can throw the computer off for things like Anti-lock breaking, etc... I'm sure they just want the $$, but with the amount of electronics in the new JL, I figured better safe than sorry.

I was in the Outer Banks 2 weeks ago and Stopped by the KDH dealership (Kill Devil Hills). They did my speedo in 25 minutes. Most of the money goes to Chrysler for the computer work. What a very knowledgeable dealership. They wouldn't say it directly but from our conversation I figured out that Chrysler Jeep is getting in on the upgrades everyone is making but forcing us to take it to the dealer to have them put into the computer at a considerable cost. I upgraded all my lighting to after market LED's. These companies spend a lot of time to get them to work on the JL's without having to take them to the dealers to have them flashed to the computer. The dealer I bought it from says I need to flash them to the computer. But the after market has figured out to make after market products to work the the new computers and the Can-Bus system. There will be some things that need to be flashed but overall they should be far and fewer than they think.

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