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Old 11-10-2005, 01:52 PM   #7
MNBoxster
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Join Date: Sep 2005
Location: Minneapolis/St. Paul, Minnesota, USA
Posts: 3,308
Quote:
Originally Posted by chily3
Yes stock wheels and tires, about 85% left. So there should be no error. Bascially to check the speedo use the paddle markers along the road driving at constant speed over the measured mile. Use the seconds over a mile divided into 3600 gives you the speed. Do this for a few miles and can get really close to speedo error if any.

mike
Hi,

This will give you a fair approximation, but so many variables can upset it and you're only looking for a 3MPH error. Failure to drive the Surveyor's Line on which the Mile Posts are established, Lane Changing or Lane Wandering, Tire Pressue and even Barometric Pressure (to a very slight degree) can all add up to some error.

I'm not disputing your speedo may be off, but I think if you want to really nail it, you're gonna need to have the Dealer get involved w/ the DME. I'd wait until you need to get him in there for something else and then have it corrected. Hope this helps... Jim'99
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