GPS Speedo verification.....

Has anyone done this? I had my GPS in the truck when Allen did the street tune and he tweeked the tire size to get the speed to match the GPS. There was a significant difference in values between the actual tire size and the required tire size to get the speeds to match...like .75 inches in dia. But speedo matches the GPS within about 1-1.5 mph. The speedo was about 4 mph slower than GPS. But....now I know my mileage really sucks! I used to get about 330 miles per tank and now I'm only getting about 290 and driving styles are still the same. I kind of like the little dream world I was living in.

<div class='quotetop'>QUOTE(spinz71 &#064; Sep 14 2006, 02&#58;47 PM) [snapback]65124[/snapback]</div>

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Has anyone done this? I had my GPS in the truck when Allen did the street tune and he tweeked the tire size to get the speed to match the GPS. There was a significant difference in values between the actual tire size and the required tire size to get the speeds to match...like .75 inches in dia. But speedo matches the GPS within about 1-1.5 mph. The speedo was about 4 mph slower than GPS. But....now I know my mileage really sucks&#33; I used to get about 330 miles per tank and now I&#39;m only getting about 290 and driving styles are still the same. I kind of like the little dream world I was living in.
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mods & body style?

My work van (E350) is 3-4 mph high. It took my awhile after they put me in it to realize, until then I was like a rolling traffic blockade. I bet they ship them this way to improve the fleet average fuel economy. I wonder if Ford can recalibrate it?

<div class='quotetop'>QUOTE(MikeGyver &#064; Sep 14 2006, 03&#58;22 PM) [snapback]65134[/snapback]</div>

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My work van (E350) is 3-4 mph high. It took my awhile after they put me in it to realize, until then I was like a rolling traffic blockade. I bet they ship them this way to improve the fleet average fuel economy. I wonder if Ford can recalibrate it?
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I noticed my work truck is the same way its an 04 F-150 v6 sclb its about 3-5 off from what the road side radar checker things say.

Mods included in sig......

Allen checked mine on the dyno, said it was dead on.

Allen calibrated mine using my GPS in front of SA drag strip when the weather was crap and the track was closed. It&#39;s very accurate now. True fuel mileage sucks. :lol: