I fixed the inaccuracy of the speedometer on the SD.

Posted in in Tech:

speedometer calibration

Cool, that's a big advantage of having an electronic speedo. Due to shear luck, my 300D speedo is almost perfect with 205s, it always read high with stock tires.

OK, I have the engineering answer, but, if you ask me for my "data" to prove that I'm correct, then I'll have to shoot you.................

The stock 195 has a diameter of 24.7"

The larger 205 has a diameter of 25.3".

If the larger 205 is 75% worn on a 12/32" tread depth, it's diameter is reduced to 24.73 resulting in an exact speedo calibration.

You never doubted these Germans............did you???????

That must be it.

Seriously, I've noticed over the years that lots of speedos (especially motorcycles) tend to err on the high side. I wonder if it's some kind of a liability issue (i.e., they are calibrated so the never read low regardless of slightly oversize tires, instrument drift, etc.). I don't have data either.

Well, that's excellent.......now I can make any claim that I want.

You can't refute it.