GPS...Interesting

[Greg Meyer]

Well...with nothing better to do Saturday...I downloaded an update for my Garmin GPS 176...loaded it into the unit. Sunday I drove to BPS for "stuff"...decided to test the new firmware...



Guess what I have discovered...why evrybody passes my truck...Speedo on truck says...say 65mph...gps says 56.7mph...consistently "off" by 14.5%....



I've never done the check of GPS to truck speedo before...Service manager of the dealer has never heard of GPS (what cave has he been living in...??) but says he'll check it...doubts it could be off...especially not that much...



Anybody else ever done this...check car/truck with GPS? And, found a big difference

 

[Jim Clevenger]

Greg, I'm never off by more than 1 or 2mph on mine. Same with the boat. I would trust the GPS more than my speedometer.



Jim

 

[Mike Mann]

I checked my truck also and it was within a mile or two at the most. But my boat is about 5-6 off.



Mike

 

[Greg Meyer]

I've got my truck scheduled for a service/check on Friday

 

[gone bye bye]

I have been noticing that for a few years now. My 97 Yukon is off about 5 MPH (too fast).....this is true with three different brands of GPS. (Lowrance GlobalMap 100, Sony SkyMap for laptop, and now TeleType GPS for my HP Jornada)



Mini

 

[Rob LaMoy]

Greg, it's all in your head! The first of my many a deadly curse. Actually, my speedometer in the truck in digital and seems a little off at around 60 mph. I will try your idea to check it. Never thought of that. Saves me from calling my buddy that's a trooper and having him clock me on the highway!

 

[gone bye bye]

Rob,



Still call your buddy and have him clock you WITH the GPS on board. Dont know if the radar gun is calibrated or not, and where it stands as far as GPS speed. Might be able to get a few more MPH on the way to the lake without worrying about a ticket!



Reprot back here when you do.....



Mini

 

[Greg Meyer]

Commander Mini....



What's a R-E-P-R-O-T ? I mean is it something we can watch or is it rated "R"...?

 

[Rob LaMoy]

Had a couple of "pops" early eh Mini?

 

[mike chip]

When i lifted my truck to 40 inch tires i used my gps to recalulate my sppedo and no tickets in the last 5 years. (knock on wood)

 

[gone bye bye]

Geeze a simple typo from a guy that has fat fingers and now I am an alcoholic! lol



Going fishing now.....sorry Rob....but I dont have a boat either, just ALOT of people that want to fish with me.....at this rate all my honey holes are gonna have boats all over them even worse than before!



Mini

 

[Rob LaMoy]

I know the feeling! LOL I'll cope though

 

[Bill McElroy]

that's what you get for posting your "success rate" all the time!!...

 

[C C]

Another reason for the speedo not matching the GPS is if the vehicles tires & rims are not the same as the factory issued there is a very good chance the speedo will be off.



I replaced the factory tires on both of my Dodge Ram trucks with bigger rims & tires then what came from the factory, one is two miles over, one is two miles under on the speedo vs. the GPS.

 

[Rob LaMoy]

I think I'm gonna start lieing Mac! LOL.....Horrible day, just HORRIBLE!