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Old 08-05-2013, 12:26 AM   #31
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Originally Posted by Cdwright View Post
I think there might be a legal requirement for you to do this anyway.
Huh?...is there a speedometer police

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Old 08-05-2013, 12:31 AM   #32
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Can any one help me with my PRIUS getting stuck on logging roads????

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Old 08-05-2013, 12:33 AM   #33
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were do they recalibrate speedometers? thanks for the help
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Old 08-05-2013, 12:43 AM   #34
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Any dealership can do the calibration, since you bought the rims and/or tires at the dealer you bought the Jeep from I would go back to them and ask them to finish the job and calibrate the speedo, of course they may have already done this, use a GPS to check your speedo accuracy first. A lifted Jeep gets a lot worse mileage than a stock Jeep, I don't know if yours is lifted or just the bigger tires but your ground clearance is a lot higher than a stock off the lot JK, so, something has lifted it. In the future you would do well to google the question and reading the many many existing threads before starting a new one when you don't have all the info you need to get the info you want.
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Old 08-05-2013, 12:53 AM   #35
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Any dealership can do the calibration, since you bought the rims and/or tires at the dealer you bought the Jeep from I would go back to them and ask them to finish the job and calibrate the speedo, of course they may have already done this, use a GPS to check your speedo accuracy first. A lifted Jeep gets a lot worse mileage than a stock Jeep, I don't know if yours is lifted or just the bigger tires but your ground clearance is a lot higher than a stock off the lot JK, so, something has lifted it. In the future you would do well to google the question and reading the many many existing threads before starting a new one when you don't have all the info you need to get the info you want.
thanks i will go to the dealer tomorrow see what they say ..
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Old 08-05-2013, 01:05 AM   #36
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Rubicon sticker on a sport actually reduces the mileage by 2-5 MPG. It's actually in the owner's manual.
sounds good ..
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Old 08-05-2013, 01:50 AM   #37
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Ok, I think there is a lot of confusion here. I hope I can help out a little.

First of all there are no legal ramifications for recalibrating the speedometer. If you change your gears or tires, you need to do this, and it is all legal. You are just getting your own gauges to record everything accurately, you aren't messing with the odometer.

Will recalibrating your speedometer change your true mpg? No, but it will give you an accurate reading. What I mean is, you maybe truly getting 16 mpg right now, but because you are calculating it off of a speedometer that is no longer accurate, you THINK you are getting 12 mpg when in fact you are getting 16.

However, what I will say is, 12 mpg is not wildly unreasonable for a 2012 JK unlimited 4 door with bigger heavier aftermarket tires and wheels. My 2012 with auto transmission, 3.73 gears (max tow package), 35" Khuomo venture tires on 17" AEV savegres got about 13 mpg in the city. The tires and city driving on a JK have a big impact on efficiency. On road trips, I would get closer to 16-17 mpg with my set up.

Another thing I will warn you is that many dealers will NOT recalibrate your speedometer for anything larger than 32", as 32" is the maximum size of stock tires. This is where the procal or other computer calibrations come in the picture.
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Old 08-05-2013, 02:10 AM   #38
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Ok, I think there is a lot of confusion here. I hope I can help out a little.

First of all there are no legal ramifications for recalibrating the speedometer. If you change your gears or tires, you need to do this, and it is all legal. You are just getting your own gauges to record everything accurately, you aren't messing with the odometer.

Will recalibrating your speedometer change your true mpg? No, but it will give you an accurate reading. What I mean is, you maybe truly getting 16 mpg right now, but because you are calculating it off of a speedometer that is no longer accurate, you THINK you are getting 12 mpg when in fact you are getting 16.

However, what I will say is, 12 mpg is not wildly unreasonable for a 2012 JK unlimited 4 door with bigger heavier aftermarket tires and wheels. My 2012 with auto transmission, 3.73 gears (max tow package), 35" Khuomo venture tires on 17" AEV savegres got about 13 mpg in the city. The tires and city driving on a JK have a big impact on efficiency. On road trips, I would get closer to 16-17 mpg with my set up.

Another thing I will warn you is that many dealers will NOT recalibrate your speedometer for anything larger than 32", as 32" is the maximum size of stock tires. This is where the procal or other computer calibrations come in the picture.
thanks for your help .. i agree with you about the speedometer
i
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Old 08-05-2013, 09:28 AM   #39
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Will recalibrating your speedometer change your true mpg? No, but it will give you an accurate reading. What I mean is, you maybe truly getting 16 mpg right now, but because you are calculating it off of a speedometer that is no longer accurate, you THINK you are getting 12 mpg when in fact you are getting 16.

However, what I will say is, 12 mpg is not wildly unreasonable for a 2012 JK unlimited 4 door with bigger heavier aftermarket tires and wheels. My 2012 with auto transmission, 3.73 gears (max tow package), 35" Khuomo venture tires on 17" AEV savegres got about 13 mpg in the city. The tires and city driving on a JK have a big impact on efficiency. On road trips, I would get closer to 16-17 mpg with my set up.

Another thing I will warn you is that many dealers will NOT recalibrate your speedometer for anything larger than 32", as 32" is the maximum size of stock tires. This is where the procal or other computer calibrations come in the picturem.
Correct. I thought of the mpg thing afterward. I thought that article explained it pretty well.

I do think 12 mpg is a little unreasonable. He already said the Jeep isn't lifted. I'm running almost exactly the same setup and getting almost 19mpg. Mine is a Sport, manual, alloy wheels, 3.73 gears and a DANA 44 front axle. Those are the only differences and none of those things should make a 7mpg difference. I'd know Jeeps are rolling boxes but I'd definitely be questioning my mpg, too, if I was only getting 12 on this setup.
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Old 08-05-2013, 09:28 AM   #40
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When my mileage seemed to drop off once it turned out that the EVIC got switched to metric. Instant gratification.
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Old 08-05-2013, 09:36 AM   #41
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Good catch Panther. lollllll
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Old 08-05-2013, 11:25 AM   #42
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Please let us know what the dealership says and does to help you,helps to keep us all intune with your dilemma!
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Old 08-05-2013, 11:47 AM   #43
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If it's has a 3.21 gearing and they went from the stock 29" tires to 32's without recalibrating the computer to the new size it will mess with your milage, speedometer, gear shifting pattern, etc. especially in automatics. AEV Makes the Procal that is really easy to use and will fix all that. I'm just wondering why there is a Rubicon sticker on a Wrangler with 3.21 gearing. Was it used? I have a 2013 sport with 3.21 gearing and I get about 16 mpg mixed driving.
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Old 08-05-2013, 12:39 PM   #44
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Please let us know what the dealership says and does to help you,helps to keep us all intune with your dilemma!
so i went to the dealership and they said they dont recalibrate the speedometers anymore and if i do it will void the warranty so if something is to go wrong in the future they will say its because the oversiZe wheels .. the guy just told me to leave it like that and try to drive cruise especially taken off from stops i guess i will try to drive slower
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Old 08-05-2013, 02:42 PM   #45
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Order the AEV Procal and do it yourself. You can reprogram alot of little things in the computer that make a big difference. And you can easily return it to factory specs if you want. It's a $150 investment that will pay for itself. Thousands of Wrangler owners can't be wrong.
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Old 08-05-2013, 02:50 PM   #46
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I have the Procal module and if I were you, I'd just get that. That way you can do it yourself in the future if you decide to go bigger on tires, or regear.
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Old 08-05-2013, 02:57 PM   #47
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Your calculated miles per gallon is wrong. Also, are you sure you have 3.21's? That would be horrible, especially with 32's or larger. Your jeep would move about as fast as a tortoise. You would also eat up gas in the city trying to keep up with all the other traffic due to your slow acceleration.
Get your jeep Speedo recalculated and check your mpg after.
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Old 08-05-2013, 03:13 PM   #48
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His Jeep is a Sport model with Rubicon stickers on it. He said earlier it had 3.21 gears, which would be right for a Sport model without a towing package or 32" tires from the factory. I agree that his speedometer is probably wrong.
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Old 08-05-2013, 03:48 PM   #49
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..
i started this thread for help if your not gona help mind your own business if its a rubicon or a sport i bought mine cash so i can do whatever i want to it ✌

If it is a Rubi or not will help determine your gear ratio AND your wheel size. That was my point. We can sometimes determine axle ratio simply based on the year, model, and transmission of the vehicle. +2012, all auto Rubi's come with 4.10's or 3.73's (All manuals and all other years for the JK auto's come with 4.10's.) +2012, all non-Rubi's come with 3.21's or 3.73's.

Knowing if your vehicle was a Sport or Sport S would have told us the original stock wheels size. Base Sports come with 29"'s, Sport S's/Sahara's and Rubi's come with 32"'s.

So, if your vehicle was a base Sport on 29"'s and you went to heavy 32"'s without recalculating your speedo, it means your odometer/speedometer are incorrect, and your computer is also miscalculating your fuel economy and maybe even your shift points. Get a Procal....and keep in mind that you have a heavier 4 door on 3.21's. 3.73's would have probably been better. (That is what I meant by people needing to come here for 90 days prior to going near a dealership. You want heavier tires on a 4 door....get 3.73's up front...or pay $1500 down the line to regear).

If your vehicle is actually a Rubi on 3.73's or 4.10's, and you were still getting 12mpg combined on 32"'s...that would be a different scenario. 12mpg combined is pretty low, even for a stock brick on wheels.

So as you can see, knowing what model you have up front helps us determine what is wrong down the line.
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Old 08-05-2013, 04:11 PM   #50
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I have the Procal module and if I were you, I'd just get that. That way you can do it yourself in the future if you decide to go bigger on tires, or regear.
yea i think im going to purchase the procal module soon again thanks alot guys ..
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Old 08-05-2013, 07:20 PM   #51
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Ok, I think there is a lot of confusion here. I hope I can help out a little.

First of all there are no legal ramifications for recalibrating the speedometer. If you change your gears or tires, you need to do this, and it is all legal. You are just getting your own gauges to record everything accurately, you aren't messing with the odometer.

Will recalibrating your speedometer change your true mpg? No, but it will give you an accurate reading. What I mean is, you maybe truly getting 16 mpg right now, but because you are calculating it off of a speedometer that is no longer accurate, you THINK you are getting 12 mpg when in fact you are getting 16.

However, what I will say is, 12 mpg is not wildly unreasonable for a 2012 JK unlimited 4 door with bigger heavier aftermarket tires and wheels. My 2012 with auto transmission, 3.73 gears (max tow package), 35" Khuomo venture tires on 17" AEV savegres got about 13 mpg in the city. The tires and city driving on a JK have a big impact on efficiency. On road trips, I would get closer to 16-17 mpg with my set up.

Another thing I will warn you is that many dealers will NOT recalibrate your speedometer for anything larger than 32", as 32" is the maximum size of stock tires. This is where the procal or other computer calibrations come in the picture.
I thought it was illegal not to recalibrate it since it might affect the odometer. I think i might be nuts though.
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Old 08-06-2013, 01:41 AM   #52
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Funny how dealers can be different. We put 32" Sahara wheels/tires on my niece's JK this weekend. She went to the dealer today and they calibrated her speedo for free. She had the stock 29". Her speedo was about 5 MPH off as a result.

The wheels will turn slower (less revolutions per mile, not speed) with taller tires. Slower means that the miles are going to read less on the odometer than you actually travelled, therefore giving the impression of less MPG than you are actually getting. Recalibrating gets the speed right, but also will give a proper odometer reading and therefore let you determine your actual MPG.

Also, if you have an auto, the shift points will be off if you don't recalibrate. That will have a negative effect on you fuel mileage as well.
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Old 08-06-2013, 01:59 AM   #53
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i started this thread for help if your not gona help mind your own business if its a rubicon or a sport i bought mine cash so i can do whatever i want to it ✌
By the way,

You come on a public forum of Jeep guys and then tell someone to mind their own business. And they guy you told off is one of the most helpful guys here.

What you do is up to you, but don't get upset when people call you on something like that. It's like putting SS emblems on a V6 Camaro, or Z71 stickers on a regular 4x4, or Powerstroke emblems on a gas truck. Well, you get the idea.

Oh, and I tried to help with your issue too.
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Old 08-06-2013, 02:25 AM   #54
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Don't be mean to panthermark, he is as sharp as a tack.

Adding rubicon stickers is your choice, but everyone on this forum will know you're a Sport in disguise if we see you on the trails. You'll get more respect for being proud of what you have instead of pretending you achieved something you haven't...like people who claim to have run marathons but get winded when they go up a flight of stairs. I suggest replacing the rubicon sticker with something you like, see "SKYWALKER," or "RED ROCKET."

I could derive angular momentum and rotational speed for you to help define why your on-board computer is confused, but it's easier just to say "crap in, crap out." You need to make sure your vehicle configuration is being accurately processed by your computer, so it can make vital decisions (most of which are much more important than calculated fuel economy). Sensor outputs are only as valid as the computer's understanding of what it is seeing.

Good luck.
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Old 08-14-2013, 12:41 PM   #55
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Now im getting 16hwy-12 city mpg i think the motor needed time to get going to what im suppose to get
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Old 08-14-2013, 07:00 PM   #56
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Don't be mean to panthermark, he is as sharp as a tack.

Adding rubicon stickers is your choice, but everyone on this forum will know you're a Sport in disguise if we see you on the trails. You'll get more respect for being proud of what you have instead of pretending you achieved something you haven't...like people who claim to have run marathons but get winded when they go up a flight of stairs. I suggest replacing the rubicon sticker with something you like, see "SKYWALKER," or "RED ROCKET."

I could derive angular momentum and rotational speed for you to help define why your on-board computer is confused, but it's easier just to say "crap in, crap out." You need to make sure your vehicle configuration is being accurately processed by your computer, so it can make vital decisions (most of which are much more important than calculated fuel economy). Sensor outputs are only as valid as the computer's understanding of what it is seeing.

Good luck.
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Old 08-14-2013, 10:22 PM   #57
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tire size does affect MPH

When you increase diameter of tire you have to run a lower gear ratio in your axles . Your gas milage will suffer horribly until you do so.Try seeking professional
help like calling or going to a 4X4 shop and expect to pay good money for parts and installation. Its not a throw together job .You have bearings and races to install and ring and pinions and seals plus setting gear depth for optimal wear
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Old 08-15-2013, 07:53 AM   #58
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Originally Posted by cosmokramer View Post
ok, i think there is a lot of confusion here. I hope i can help out a little.

First of all there are no legal ramifications for recalibrating the speedometer. If you change your gears or tires, you need to do this, and it is all legal. You are just getting your own gauges to record everything accurately, you aren't messing with the odometer.

Will recalibrating your speedometer change your true mpg? No, but it will give you an accurate reading. What i mean is, you maybe truly getting 16 mpg right now, but because you are calculating it off of a speedometer that is no longer accurate, you think you are getting 12 mpg when in fact you are getting 16.

However, what i will say is, 12 mpg is not wildly unreasonable for a 2012 jk unlimited 4 door with bigger heavier aftermarket tires and wheels. My 2012 with auto transmission, 3.73 gears (max tow package), 35" khuomo venture tires on 17" aev savegres got about 13 mpg in the city. The tires and city driving on a jk have a big impact on efficiency. On road trips, i would get closer to 16-17 mpg with my set up.

Another thing i will warn you is that many dealers will not recalibrate your speedometer for anything larger than 32", as 32" is the maximum size of stock tires. This is where the procal or other computer calibrations come in the picture.
^^^ this
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Old 08-15-2013, 10:31 AM   #59
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Get an AEV Procal. $150 and two minute you will be back up to what you expect. Your speedometer doesn't match your tires so the computer isn't calculating it right.
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Old 08-15-2013, 11:15 AM   #60
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Get an AEV Procal. $150 and two minute you will be back up to what you expect. Your speedometer doesn't match your tires so the computer isn't calculating it right.
Agree, just make sure to actually measure your new tire height when you program the procal, and don't go with what the calculated # "should be". Many 33's are 32's, 35's are 34's, etc...

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