Quote:
Originally Posted by Echo
Ok, thanks Matty, I think I've got that.
But what will changing the wheel circumference in the Nav module actually do?
I've put my new(17"), and old (20"), tyre details into this calculator:
https://tiresize.com/comparison/
That was inches. This one is mm:
https://tiresize.com/comparison/
So, I put in 2167.........yes/no?
And thanks for explaining the Youtube VCDS stuff 
EDIT: Sorry, can't get the links to work properly. Just click on the inches and mm to compare. |
First of all I would be very surprised if Satnav sends back speed reading to instrument cluster, any adaptation you do in Satnav will only be for Satnav.
The most accurate way would be to get a piece of string and actually measure circumference of tyre as it could be slightly different between between different makes and models. Wear level would affect it as well and different tyres have different tread depth when new. Most are 8mm but some winter tyres can be up to 12mm and Michelin Crossclimate range only have 7mm when new for some reason. But they still offer 45k mileage warranty for CC, 50k for CC+ and 60k for CC2. How they make them last so long with less tread to start with is dark magic and how you go about claiming it is a different question.
Now back to speed issues I am wondering if there is adaption channel in instrument to alter speed reading, I know you can adjust things like fuel level reading or fuel consumption by +/-15%. As far as I know it's not possible for D2 but some VWs have a multiplier option there, not sure about D3.
I never use speed warnings but I remembered about this thread when I went out this morning and tested mine. I have 2006 car with wide instrument cluster so I have digital speedo reed out as well which makes it easier. The tyres on car are almost new 235/50R18 Crosslimate +, done about 3k miles. I do not know what the stock size was on this car but I can see that wheels are not original but from newer Audi replaced by one of previous owners as they have bigger centre bore 66.1mm instead of 57.1mm and use spigot rings. Digital speedo and analog show the same speed, comparing it to GPS reading in the phone speedo is showing 1-2mph more than GPS at 70mph.
Setting speed limit with 'Çheck' button at 70mph warning comes on at 72mph but there is a bit of error do to manual setting. Setting speed limit to 70mpg in MMI the warning comes on at 71mph