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Is Recalibration Needed for going to 33’s

Beowulf85

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New guy here. So today I picked up my gobi gladiator sport us and immediately went to my local dealership. I put 285/70/17 falken at3 on. I checked my speedometer on back roads and on the highway . My speedometer matches up with my gps perfectly. Even in cruise control. Even at 70 if it's off by 1mph would I need to even recalibrate it?
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New guy here. So today I picked up my gobi gladiator sport us and immediately went to my local dealership. I put 285/70/17 falken at3 on. I checked my speedometer on back roads and on the highway . My speedometer matches up with my gps perfectly. Even in cruise control. Even at 70 if it's off by 1mph would I need to even recalibrate it?
Are you using a phone app for your speed measurement, and was it plugged into the USB port? If so, your app may be drawing the speed from your Jeep instead of measuring independently. Mine does this.
 

Beowulf85

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Are you using a phone app for your speed measurement, and was it plugged into the USB port? If so, your app may be drawing the speed from your Jeep instead of measuring independently. Mine does this.
Nope my gps was disconnected from my truck. I did not even have bluetooth on. At 50 mph it was off by maybe half because I had jeep on cruise and gps was going back and forth 1 mph. If off by only 1 mph is it even worth recalibrating?
 

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Nope my gps was disconnected from my truck. I did not even have bluetooth on. At 50 mph it was off by maybe half because I had jeep on cruise and gps was going back and forth 1 mph. If off by only 1 mph is it even worth recalibrating?
I would leave it as is.
 

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RodRecket

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New guy here. So today I picked up my gobi gladiator sport us and immediately went to my local dealership. I put 285/70/17 falken at3 on. I checked my speedometer on back roads and on the highway . My speedometer matches up with my gps perfectly. Even in cruise control. Even at 70 if it's off by 1mph would I need to even recalibrate it?
I did the same swap at the dealer before I brought my truck home. When I asked about speedo recal (part of why I had the dealer do the tire swap) they looked it up and it does not require a recal if using the stock rubi sized tire, 285/75/17. The service manager read the mopar guidelines to me so I dont think he's full of crap.
 

Beowulf85

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I did the same swap at the dealer before I brought my truck home. When I asked about speedo recal (part of why I had the dealer do the tire swap) they looked it up and it does not require a recal if using the stock rubi sized tire, 285/75/17. The service manager read the mopar guidelines to me so I dont think he's full of crap.

That's awsome to hear. I threw on 285/70/17 on the truck before it had 50 miles on it. Hopeing I can sell the old tires now. Thanks for the info and good luck with your gladiator.
 
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Forshy1075

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Figured I’d update my experience with my new wheels. I put the 33”s on this morning and did a drive by of one of those speed limit radar signs and my speedometer was spot on at 40 mph. I am leaning more towards not recalibrating but am going to test via gps on the highway as well before I return the Tazer I got.

Jeep Gladiator Is Recalibration Needed for going to 33’s 36FCF025-E5F8-4A52-82DE-0EA37E12E80B
 

WXman

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Yes the factory Rubicon tire is only 3% taller than the factory sport or overland tire so your speedometer will only be off by a couple of miles per hour on the interstate. Not really a big deal. It's when you go to oversize tires that you need to start recalibrating.
 

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Yes the factory Rubicon tire is only 3% taller than the factory sport or overland tire so your speedometer will only be off by a couple of miles per hour on the interstate. Not really a big deal. It's when you go to oversize tires that you need to start recalibrating.
The circumference increase does affect the odometer, so you couldn’t truthfully claim the odometer is correct when turning the vehicle in for warranty maintenance or even worse: selling it. Might even mean you are violating state law on such matters. Say your larger tires are off by 3%, that is 3000 miles per 100,000 miles. May not seem like a lot but it does matter
 

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NateKY

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Hell, my Rubicon needs to be recalibrated on stock 33s. 2 mph off according to GPS.
 

Renegade

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The circumference increase does affect the odometer, so you couldn’t truthfully claim the odometer is correct when turning the vehicle in for warranty maintenance or even worse: selling it. Might even mean you are violating state law on such matters. Say your larger tires are off by 3%, that is 3000 miles per 100,000 miles. May not seem like a lot but it does matter
I’ll call BS on these scary scenarios. Most factory speedometers are a couple of miles per hour low from the factory. If his reads accurately with the new tires, there’s absolutely nothing wrong leaving it as is.
 

PyrPatriot

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I’ll call BS on these scary scenarios. Most factory speedometers are a couple of miles per hour low from the factory. If his reads accurately with the new tires, there’s absolutely nothing wrong leaving it as is.
Sure, you can do that. And I can follow my own legal analysis for the contract language confirmed by my dealership service manager’s statement on the matter to me. But you do you. I am sure there are many dealerships who dont care. I do, when i sign any form saying that the odometer is correct to the best of my knowledge and I didnt do anything to affect it, like adding larger tires without recalibrating

Please show where you are getting the “couple mph low from the factory” bit. I vaguely recall reading something from the DOT on odometers needing to have a certain standard and allowing for a margin of error, but nowhere near that much
 

Renegade

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Sure, you can do that. And I can follow my own legal analysis for the contract language confirmed by my dealership service manager’s statement on the matter to me. But you do you. I am sure there are many dealerships who dont care. I do, when i sign any form saying that the odometer is correct to the best of my knowledge and I didnt do anything to affect it, like adding larger tires without recalibrating
Like I said, if it is ACCURATE after the tire swap, it's accurate. Not an issue- legal or otherwise.
 

Beowulf85

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My stock jl sport with tires it came with from factory was off by 1mph. My jt sport with 33 falken is off by maybe 1/2 mph at 60mph but still teeters back and forth compared to gps speed. I wonder if they just have the basic calibration set somewhere in the middle for all models.
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