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2019 Jeep Grand Cherokee Trailhawk Hemi
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Is changing tire size being detected and flagged by dealerships, especially since newer models require a bypass? Coming from the VAG (VW/Audi) world, TD1 campaign was a nightmare when you wanted to ecu flash for performance or anything else. I am assuming no to an extent since it's such a popular thing to do and in this case, we're just changing values vs a full on BIOS flash (sort of like RossTech tool that allowed feature flags to be altered a lot like Alpha does).

I'm good with pay to play, I got hit on a TD1 on my stage 1 Audi and lost my powertrain warranty, been down that road. Just curious on experience (Audi was pretty much immediate and a standard to scan for to flag). I'm about to exit warranty stage on the Jeep and been kicking around a Maxcare extension due to the air ride. But slightly larger tires, exhaust, off road armor, modified tire size on ECU, it's a lot to try and argue under Moss Act if Stellantis was being difficult for say, transfer case or some other powertrain issue.
 
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GC TH
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Is changing tire size being detected and flagged by dealerships, especially since newer models require a bypass? …….. But slightly larger tires, exhaust, off road armor, modified tire size on ECU, it's a lot to try and argue under Moss Act if Stellantis was being difficult for say, transfer case or some other powertrain issue.
I worry about that too, but you could argue that they would have to void the warranty on 80% of the Wranglers and Gladiators out there, which I almost guarantee they don’t do
 

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2015 WK2 Limited V6
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43 Posts
Did this today on my MY2015. My stock setting was 2379mm. I upsized the tires to Falken Wildpeak AT3W 265/65r18. Set the new circumference at 2440mm and the speedometer is great. I took EmailGuy’s formula and reduced it by 3% to account for compression on the tire. The number should have been 2445mm but given the earlier post about 2440mm I figured 5mm wasn’t worth the potential issues.

Great instructions. Recommend you copy the status logs before you start. Here’s a YouTube instruction:

I’m using a Kindle Fire 7 with the OBD MX. Works great.
 

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2020 Jeep Grand Cherokee Trailhawk, ProCharged 5.7L Hemi
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519 Posts
2440 still gives me the park sense error. It only seems to like the oem setting of 2371...
Are you changing the tire size to 2440, clear the codes, performing and ABS initialization and then clearing the codes again?

Make sure to perform the ABS initialization procedure, and it needs to be performed in the following order:
Static ECU initialization ;
Longitudinal acceleration sensor;
Clearing Rolls information.
 

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Are you changing the tire size to 2440, clear the codes, performing and ABS initialization and then clearing the codes again?

Make sure to perform the ABS initialization procedure, and it needs to be performed in the following order:
Static ECU initialization ;
Longitudinal acceleration sensor;
Clearing Rolls information.
Yes. I tried a half dozen times. It only likes 2371
 

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2014 GC Limited 4X4
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2,115 Posts
Someone posted on FB pages about the park sensor errors coming up and I don't think he ever found a resolution.
 

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2016 WK2 Limited Diesel
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A big thank you to EmailGuy for these instructions!
I just put on a set of Toyo Open Country ATIII 285/60r18 on my 2016 WK2.
Following these instructions and seeing a few peoples' reports here and elsewhere about the number to enter, I got the feeling even the best calculations just don't quite work out, so my scientific wild ass guess was 2430 for my first attempt, and it is spot on from 0-80. Beginners luck.
AlphaOBD worked great, got the ABS warnings and did the reset and error clear.
 
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