I think the guys have it right - and I think that tire rotation also determines how fast the speedometer registers that you are travelling. I say that because when I was a young teenager, my mom drove my sister and I and some of our friends to summer camp one year in her new Honda Accord - well, it was used, but new to us
Anyway, we got pulled over by a cop for speeding, after we had just been talking about the speed limit, and we had our eyes glued to the speedometer, which had been very steady on the posted speed limit. When the cop told my mom that she had been speeding, we all sort of gasped and said no way that couldn't be - and the cop let my mom off because it was so obvious how shocked we were. When we got home, Mom took the car to the mechanic, who discovered that the tires were just the slightest bit, um, smaller? I think... than the specs required, and that is why the speedometer was inaccurate.
Seems to me that the odometer is also connected to the tires, so if my mom had troubles with the speedometer, she might have also had troubles with the odometer too. Will have to ask her and see if she remembers...
Melisma (shutting up for a while, here under her Rock)
