🚀 go-pugleaf

Michael Zarlenga wrote:

> DPH (rally2xs@csi.com) wrote:
> : > >Speeding is based on the officers judgement. the reason that within 10mph
> : > >of the limit is usually not considered speeding is because at 70 MPH the
> : > >average non-calibrated speedometer reads 65MPH. Having a speedometer
> : > >calibrated is actually quite expensive for the manufactures, so they
> : > >generally only calibrate speedometers for law enforcement purposes.
> : >
> : > Even if you calibrate it, tire wear will change it.
>
> : Not enough to matter.  Maybe 0.3 percent.  Can't even see that on an analog
> : speedo.
>
> Tire wear can be as much as 1" on a 15" rim, that translates to
> a circumference change of 6.6%.
>
> You estimate of error was off by more than 20X.

I have a Mitsubishi Eclipse with an electronic speedometer in it.  The electronic
speedometer has an electronic odometer in it that reads to .001 mi.  I can
calibrate the electronic odometer to the mileposts (usually done over 50 miles or
so) via a "factor" against a base number which is 60,000.  I wear these tires out
frequently (in abt 25,000 mi) due to the all wheel drive, and seldom see changes
over about 200 on the factor.  So I have to crank in 59,800 to make the odometer
portion of this speedometer read true miles, as opposed to about 60,000 when new.
That is 200/60,000 = 2/600 = 1/300 =.33%.  BTW, this is a 16" rim tire, although
that doesn't really make a lot of difference.

DPH