I have an A4 softtop with 235/45 tires. I've been noticing that the speedo reads about 6-7% higher than the actual speed. Is there a way to change the speedo's calibration? It seems to be set for a 55 or 60 aspect ratio tire?

 

No way to change. There are wheel speed sensors that are set to oem tire size. Check the "miata tire calc" (google) to see the size and rolling diameter difference.

 

That's just it. I believe a standard A4 sedan has a 60 or 65 aspect ratio tire OEM. My A4 cabriolet has a 45 OEM aspect ratio. If there is a sensor in there could it be the wrong one? Can it be replaced? Miata tire calc is what got me to thinking that the speedo isn't set for the right aspect ratio.
Thanks
Jim F.

 

no it is just a photoelectric or magnetic and the ecu converts it. What makes you think your speedo is off?

 

it could be the speed sensor i just kinda had the same problem except mine just stopped workin and we replaced the sensor n she works good now hook it up to the obd and see if she throws a code