Many thanks to this thread an the excellent guide in here, I had VCDS delivered today, I changed my wheels/tyres from std 235/55R17 to 245/65R17 which meant the speedo was over reading, odometer was under reading, and MPG figures were also incorrect due to this.
My K number settings are as below:
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My 245\65 tyres have a circumference of 2357mm so I initially set the K number to setting 1. Then went for a test drive, a quick 4.7 miles each way round trip.
First thing that happened is the DSG box, when shifting down a gear when accelerating, was jerky as hell!! Then, ACC gave an error once I was above 40mph or so. And finally, I had a white spanner icon flashing where the gear indicator "D7" was. Oh and the 4.7 mile each way, so 9.4 mile round trip was showing as 10 miles on the odometer.
Got back home, read the fault codes and got a "inconceivable/incomprehensible reading from ABS sensor" as a new code, so I guessed that the setting 1 was too big of a circumference for the ABS sensor.
I then set the K number to setting 2, did the same test drive and all was good with the world! Speedometer is reading 2mph higher than GPS at 70mph (72mph for 70mph GPS), and 1-2mph over at 50mph (51mph for 50mph GPS). And the odometer is now bang on, reading exactly what the GPS distance said. And no issues with the DSG box or any errors, and ACC is working perfectly.
