The Unofficial BMW M5 Messageboard (m5board.com) - View Single Post

Second Childhood · 24th July 2006, 02:12

I can't say with any assurance where the M5 takes its speedo measurement, but most vehicles take a feed off transmission near the end to monitor actual revolutions going to the rear differential. If this is, in fact, the case with the M5, the rear tire circumference would directly effect the accuracy of the speedo reading. My experience with my M5 is that the speedo reads consistently 10% higher than actual speed with standard tires. I am planning on looking into how to adjust the speedo reading to obtain a more accurate reading. If the current setup is entirely an digital vs. analog setup, this may be more involved.
This may be more simplistic than what you were looking for, but it seemed you were looking for some response.

24th July 2006, 02:12	#3 (permalink)
Second Childhood Junior Member, warming up (<31 posts) Join Date: May 2006 Location: Dallas Posts: 10 Thanks: 0 Thanked 0 Times in 0 Posts	Typical speedo measurement point I can't say with any assurance where the M5 takes its speedo measurement, but most vehicles take a feed off transmission near the end to monitor actual revolutions going to the rear differential. If this is, in fact, the case with the M5, the rear tire circumference would directly effect the accuracy of the speedo reading. My experience with my M5 is that the speedo reads consistently 10% higher than actual speed with standard tires. I am planning on looking into how to adjust the speedo reading to obtain a more accurate reading. If the current setup is entirely an digital vs. analog setup, this may be more involved. This may be more simplistic than what you were looking for, but it seemed you were looking for some response.