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Old 10-10-2022, 11:14 PM   #4
shorod
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Re: Tire Pressure and Speedometer Calibration

Quote:
Originally Posted by CapriRacer View Post
A better idea is to use the Interstate mile markers. They are at least reasonably accurate. But use several over a long distance. I like to use 10 miles, although it is sometimes difficult to maintain a steady speed for 10 minutes - even with cruise control!
I'll offer that most people these days have smart phones, and if not, they probably have a standalone GPS navigation unit. There are multiple applications available for smart phones that will display speed based off the rather accurate GPS receiver in a modern smart phone, and many stand alone GPS navigation units also have an option to display vehicle speed. I suspect that even a dated GPS receiver will provide a more accurate speed reading than counting mile markers over time. But even if someone opts to use a GPS receiver to compare against the displayed speed on a speedometer, a relatively constant speed should be maintained for several seconds since it can take a GPS unit several samples to update the calculated speed.

-Rod
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