6 hours ago
The 2mph offset (My mind is wired to SI units so i'll stick to that) might be okay depending on the speed; if i have 5km/h offset at 20km/h, i find that a lot. If it is 5km/h offset at 150km/h, i can live with that.
anyhow, back to the topic; i want my speedo to be a speedometer, not a guess-o-meter. so i'd like it to be within 1-2km/h at 100km/h (1% deviation).
My theory didn't work, it was off by about 12%! so i thought i maybe calculated it backwards and my tire circumference should be 6% larger in the cars's computer. Again, no luck. I've now got it set on 2145 (theoretically they should be 2156; tires are brand new). Still about 5% off... I might try a couple of steps lower than that (2140, 2135, 2130) to see if that gives an improvement.
To get back to the initial post; it seems that volvo indeed does it's own thing and that certain tire size and circumferences do not compute correctly. It's a bit of an iterative excercise get the speedo to show actual speed. I'm even thinking that changing the 'vehicle type' to police car might unlock better speedometer calibration, but don't want to try that one out just yet.
anyhow, back to the topic; i want my speedo to be a speedometer, not a guess-o-meter. so i'd like it to be within 1-2km/h at 100km/h (1% deviation).
My theory didn't work, it was off by about 12%! so i thought i maybe calculated it backwards and my tire circumference should be 6% larger in the cars's computer. Again, no luck. I've now got it set on 2145 (theoretically they should be 2156; tires are brand new). Still about 5% off... I might try a couple of steps lower than that (2140, 2135, 2130) to see if that gives an improvement.
To get back to the initial post; it seems that volvo indeed does it's own thing and that certain tire size and circumferences do not compute correctly. It's a bit of an iterative excercise get the speedo to show actual speed. I'm even thinking that changing the 'vehicle type' to police car might unlock better speedometer calibration, but don't want to try that one out just yet.