I have a 91 Astro van 4.3 litre engine as I travelled on vacation and
through the city I noticed my speedometer reading higher than the speed
signs. It doesn't matter what speed I travel my speedometer is 5 kph faster
than the speed zone signs read.
I started looking at these speed signs since I went for my e-test and the
mechanic said that my speedometer was off.
Any suggestions on what could cause this.
It's probably normal. In some countries (Germany for one) the
speedometer is required by law to be accurate within a certain
tolerance, but never read faster than actual speed. (they also have
laws there mandating that replacement tires must be the exact size and
speed rating as originally specified, with a few exceptions that need
to be approved for the particular vehicle and tire combination.)
Therefore a speedometer reading a small amount low (and I would
consider 5 kph to be "low") I wouldn't worry about it. If you feel the
need to compensate for this, then do so, but I wouldn't call appx. 3
MPH anything to worry about.
The tires you now have are smaller in overall diameter than the
originals. That means they will turn more revolutions per mile/km,
which will make the speedometer read higher than you actual speed.
To my way of thinking I'd rather have my speedometer read higher
than my actual speed - gives you a little "margin".
Sacramento, CA USA
No it's off 5 km in Canada and 5 miles in the States I have a digital dash.
This year was the first time in all the years of emission testing that the
told me that my speedometer was off and I always been bring it to the same
place. That why when saw a speedzone sign I would pay more attention to what
the was posted.
With all due respect, your numbers don't make a bit of sense. If your
speedometer is off, it's off. You just don't know how to measure it.
You say it's off 5km in Canada and that is 3.1 miles. Then you say it's
off 5 miles in the states. That's a big difference. Neither one of
those numbers means anything unless one also states the MPH at the
time. I give up as you will never figure it out.
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