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Stock tire size setting for Rubicon

JerseyMark

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Does anyone know, or could check to see what the stock Rubicon tire size is supposed to be set to?

I used an obd 2 scanner to check my stock rubicon tire size and it seems incorrect.
On the jscan app pulldown it says “31.25(stock size)”
On current tire size, it says 31.3”
Both of these seem incorrect, when I measure the tires, they come in around 32”
The reason I even checked is because, my wife’s Sahara has rubi takeoff tires and I wanted to check the factory settings on a rubicon. When I check hers, it says the same stock size as my Rubicon, despite having 1” smaller tires from the factory.
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whiskey jack

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Does anyone know, or could check to see what the stock Rubicon tire size is supposed to be set to?

I used an obd 2 scanner to check my stock rubicon tire size and it seems incorrect.
On the jscan app pulldown it says “31.25(stock size)”
On current tire size, it says 31.3”
Both of these seem incorrect, when I measure the tires, they come in around 32”
The reason I even checked is because, my wife’s Sahara has rubi takeoff tires and I wanted to check the factory settings on a rubicon. When I check hers, it says the same stock size as my Rubicon, despite having 1” smaller tires from the factory.
On the tazer my factory rubi tire size setting is 32.67.
 

oldcjguy

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If you have the ability to change it then just put the right number in. Measure from the center of the wheel hub to the ground and double that number. That's the effective tire height and the number the computer needs.
 
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JerseyMark

JerseyMark

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Thanks, it sounds like mine was set incorrectly from the factory. I am keeping stock tires for now, so I didn't want to pay the $21 for the jscan license if i didnt need it. I think I’ll just do it since it will be a pain at the dealership.
 

Warz2k4

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@JerseyMark
I as well, have a Sahara w/ Rubicon Wheels+Tires. What did you end up changing the tire size to with JScan?
 

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JerseyMark

JerseyMark

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I ended up with 33” on jscan.

The tires with around 39psi in them measure about 32.75” when I measure from the ground up tot he tallest point(I used a level on the center of tire)
However, when I set it to that, the speedo was about 1 mph slow at 70mph(read 69 on speedo). When set at 33”, the speedo is about 0.5 fast at 70mph(gps measured speed flickers between 69 and 70 with cruise set at 70). So, I think that is closest to stock. They usually make the speedo on most vehicles 1-2 mph faster than the actual speed.
 
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JerseyMark

JerseyMark

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Also, to clarify - when I was originally measuring my tires, I didn’t use a level and measured to the tallest spot on the sidewall which was around 32”
When I set it to that, the speedo was further off(showing around 2mph slower than actual speed)

with the level, I measured the tallest spot on the tire which was the top, center of the treads.
 

Warz2k4

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Also, to clarify - when I was originally measuring my tires, I didn’t use a level and measured to the tallest spot on the sidewall which was around 32”
When I set it to that, the speedo was further off(showing around 2mph slower than actual speed)

with the level, I measured the tallest spot on the tire which was the top, center of the treads.
Ugh, I don't have a JSCAN to make changes, and I don't like that my speedometer is not accurate.
 

Beebe Senior

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When I put my stock rubi tire size in to tirerack, it tells me they are 33's
 

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JerseyMark

JerseyMark

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@JerseyMark Exactly what tools do I need to buy, to get the JSCAN?
The jscan website tells you the recommended adapters. You need two:
1. OBD II bluetooth adapter - Vgate iCar Pro LE is recommended - about $30
2. Chrysler security bypass cable - Autel chrysler 12+8 - about $40

there are pics and instructions on how to connect the adapter and cable on the jscan website
then download the app and follow the instructions
 
 



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