Speedo Adjustment

The usual "as built" speedo setting is set at 3.5% below actual and at +2kph (Market:0).

Although each of these parameters has a number of settings, it appears as if there are only two main market settings. In Genesis, this is displayed under Jaguar Speedometer Calibration Market which can be found under the Warnings and Messages tab. The choices are:
Market 0: 3.5% + 2kph
Market 1: 2.0% + 0kph

Accordingly, if the above is set to Market 0, then the following parameters are also set:
Jaguar KPH Offset: +2kph
Jaguar Percentage Scaling Factor: 3.5%

To effect a change, all three setting must be changed.
I changed all three settings as follows:
Market 1: 2.0% + 0kph
Jaguar KPH Offset: 0kph
Jaguar Percentage Scaling Factor: 2%
This gives a spot on speedo on 19” 255/55/19 and 18” 265/60/18

Quote:

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Originally Posted by Tombie

Understand Rod, for reference 18” wheels makes no difference - rolling diameter does.

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So what value do you use for rolling diameter given that it's probably not the actual rolling diameter of the tyre fitted? Do increase or decrease it by a certain amount to fudge the correct speedo reading?

Quote:

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Originally Posted by rocket rod

So what value do you use for rolling diameter given that it's probably not the actual rolling diameter of the tyre fitted? Do increase or decrease it by a certain amount to fudge the correct speedo reading?

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I adjusted by the % error as a baseline. And went from there...

Take the number in there, convert to diameter. Work out ratio of that size to real, then go back in and change by that percentage.