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Recently, outfitted my '20 Elite w Nitto Nomad Grapplers 265 50 20 and realized all data has mpg etc can't be calibrated to new tire size. My tires are 1" taller. Does anyone have a calculator to adjust these readings to accurate?
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2021 AWD Sport Crystal Black / 2021 AWD EX-L lSteel Metallic
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Most navigation systems shows your actual speed so you can compare that to your speedometer. I run 255/55/20 and mine is off 3 mph at highway speeds.
 

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FWIW, my Elite with new 265/50/20 Michelins shows 2 mph difference between dash and GPS. The GPS shows I'm traveling faster than indicated, i.e. 70 indicated is actually 72 on GPS. At lower speeds it is only about 1mph difference.
 

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FWIW, my Elite with new 265/50/20 Michelins shows 2 mph difference between dash and GPS. The GPS shows I'm traveling faster than indicated, i.e. 70 indicated is actually 72 on GPS. At lower speeds it is only about 1mph difference.
Your 265/50R20 Michelin tires are 2% larger diameter than the OE 265/45R20 Continental tires, so your speedometer will read 2% slower than actual speed. Your actual speed when 70 mph is indicated will be 71.4 mph. At 35 mph indicated, your actual speed will be 35.7 mph. It's all about percentages...
 

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Thanks for the information and percentages. Unfortunately both my GPS and instrument panel don't have decimal points.:oops:
 

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There is a company called HealTech Electronics, and they make a device called "SpeeoHealer" for Non-mechanical MOTORCYCLE speedometers. I have installed on on the last several bike I have owned. What it does is; you calculate the speed difference shown on your dash VS your GPS. You input this into their on-line calculator which give you an adjustment % to input into the installed device. It works extremely well.... at all speeds. (You notice the error more the faster you go). It is a very common issue for motorcycles as even the smallest tire sized change can have drastic speedo/odo error. Also, sprocket size changes on chain drive bikes create wild speedo/odo errors. All that being said This particular company & item is for motorcycles only.... But you might want to contact them to see if they can recommend one made for an automobile. Just a thought..... Good luck.

HealTech Main Page - http://www.healtech-electronics.com
SpeedoHealer item I mentioned - https://www.healtech-electronics.com/products/sh/

P.S. - Be sure to consider any warranty issues if you choose to try this.
 

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There is a company called HealTech Electronics, and they make a device called "SpeeoHealer" for Non-mechanical MOTORCYCLE speedometers. I have installed on on the last several bike I have owned. What it does is; you calculate the speed difference shown on your dash VS your GPS. You input this into their on-line calculator which give you an adjustment % to input into the installed device. It works extremely well.... at all speeds. (You notice the error more the faster you go). It is a very common issue for motorcycles as even the smallest tire sized change can have drastic speedo/odo error. Also, sprocket size changes on chain drive bikes create wild speedo/odo errors. All that being said This particular company & item is for motorcycles only.... But you might want to contact them to see if they can recommend one made for an automobile. Just a thought..... Good luck.

HealTech Main Page - HealTech Electronics - Smart Tech for your Ride!
SpeedoHealer item I mentioned - SpeedoHealer v4 (SH) - HealTech Electronics Ltd.

P.S. - Be sure to consider any warranty issues if you choose to try this.
I don't think this has a Passport compatible connection harness, even if you manage to connect it you might end up with the Passport throwing a million error messages considering how sensitive its electronics system is. A mental note of the percentage of error you are dealing with while driving is the only way to go.
 

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I don't think this has a Passport compatible connection harness, even if you manage to connect it you might end up with the Passport throwing a million error messages considering how sensitive its electronics system is. A mental note of the percentage of error you are dealing with while driving is the only way to go.
I agree fx_chip.... However, I was not suggesting the installation of a motorcycle device on his car. I was simply pointing out that these devices do exist for bikes, and suggesting he might contact them to see if they know of any made for automobiles. They do work on Honda bikes (very code finicky and sophisticated electronics as well) and have a very good track record of being accurate and very stable.... but YMMV. He asked.... I answered. <grin> Besides, at resell time, depending on the ODO error direction, it may work out to his advantage LOL.
 

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If you have a ScanGauge II in your Passport, the ScanGauge II can be adjusted to compensate for changes in tire size.
It won't change the readings in gauge cluster (speedo or odometer), but the ScanGauge itself will show the adjusted MPH/KPH.

On the ScanGauge, tap the Red Circled Home button, then go to SETUP, then ADV SETTINGS, then EDIT, then SPEED.
There you can adjust the ScanGauge II MPH setting, up or down, by up to 10%.
ScanGauge II MPH readout is set at 4% on the truck.
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I love Those tires! They look great and they look like they would function good on dirt. I am not to worried about gas mileage or speed too much. around here, no one does it seems. I am already getting great gas mileage any way.
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