[PaulE]

I agree that the Porsche speedometer reads higher than actual speed, and that tire wear will affect both speed and odometer readings. But I believe the odometers are more accurate than the speedometers. There have been lawsuits against auto manufacturers in the past for odometers reading higher than actual to make warranties end sooner. And the speedometer readings seem to be a constant 2-3 mph off regardless of actual vehicle speed. If the speedometer being high was directly related to the odometer reading, then the variance between indicated speed and actual speed would be greater the higher the speed of the vehicle. Just my $0.02.