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Might be answered elsewhere, but I have 19" wheels on my 2016 Touareg, 265/50r19 tires.

I also have a set of Porsche 18" wheels with 255/55r18 snow tires, currently mounted on the car.

I know the Porsche wheels have a 1.3% smaller circumference so it needs to rotate more to get 1 mile traveled (695 revs per mile vs 686). It isn't going to make my odometer reading go crazy, but was wondering if there was a way to tell the computer it has smaller (or larger) wheels to correct the mileage readings.

Or, to put it another way, how does VW set up the car for different wheel sizes so it has correct inputs for the odometer?
 

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Cannot adjust
 

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Or, to put it another way, how does VW set up the car for different wheel sizes so it has correct inputs for the odometer?
I think you will find that the different OEM wheel sizes nominally are very similar right from the 17" size through to 20", here's something I prepared earlier....

OEM size Rim SizeO DSidewallcircum
275/40/20275.00.40
508.0​
729.01092286
275/45/19 275.00.45
482.6​
730.11242294
235/60/18 235.00.60
457.2​
739.22322
255/55/18 255.00.55
457.2​
737.71402316
235/65/17 235.00.65
431.7​
737.22314
255/60/17 255.00.60
431.7​
737.71522316

What I do when running oversized tyres is to calculate the % increase in the size and factor that % in my manual calcs for fuel consumption, with the speedo, I don't look at the speedometer reading on my cluster but I rely on GPS speed.

TonyB
 

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This is using OBD11 but VCDS should have similar settings.

Calibration of wheel circumference
17 Dashboard
Long coding
Control units
Look for "Wheel circ"
Version currently stored
Close and return to Dashboard
Live Data
search "circ" and tick box
Look for it to show
Average wheel circumference for trip distance - This is the actual circ for your tyre/wheel setup
Maximum wheel circumference for speed - This is the version related to the long coding value

Return back to Long coding in dashboard 17
Wheel circ
Change values from current version and reconfirm with Live Data until the values match
 

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This option is not available on USA spec vehicles. There's a few threads on Ross-Tech forums about this, and I tried but had no such options in the coding of the instrument cluster.
That's what I thought too
 
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