mph

[bucketmouth64]

My speedometer and garmin gps show different mph. I can have cruise control on my fl50 set at 72mph and gps unit shows about 70mph. Which one would be the more accurate mph? Right now I'm going with the gps unit.

[Macgyver55]

The GPS is likely closer to actual speed. Tires that are worn beyond half way may be enough to change the speedometer a mile an hour or so, or if you have changed from the stock size to a different one. Otherwise, your speedometer can be calibrated if necessary.

[Scott K]

It could be either, you are talking about 2-3% off, in which most GPS's are accurate to +/- 2%

[Macgyver55]

I'd still bet on the GPS........."Garmin's specifications quote 0.1mph accuracy but 0.5mph accuracy in typical automobile applications would be what you can count on".

Either way its not off enough to worry about a ticket since the truck reads fast.

[fivebucks]

On my truck (different brand) I seem to notice my speedometer always seems to run 1-2 mph faster than those electronic signs you see warning you of your speed. I just figured the truck was a little off.

[bucketmouth64]

Thanks for the responses, I will need new tires by next winter so I'll see when I put new tires on if that makes a difference.

[Tom7227]

My 02 F150 has been 2 mph faster since it was born. It has been that way on all the radar activated signs you come across as well as the gps. It's Ford's anti-ticket device IMO.

[Macgyver55]

My 02 F150 has been 2 mph faster since it was born. It has been that way on all the radar activated signs you come across as well as the gps. It's Ford's anti-ticket device IMO.

And if the odometer is off the same percentage, you'll think you get better mileage too!

[ottertailguy]

Set the cruise at 60 mph on a freeway or highway and time yourself between mile markers. If you time is over a minute your speedometer is slow and if under a minute it's fast. Pretty easy and good to know if it's wrong.

[delcecchi]

A couple percent on a timed mile is only like 1 or 2 seconds. I guess you could use a stopwatch on your phone, but otherwise it would be pretty hard to measure that closely.

I would totally believe the GPS. You could also use the odometer and time function (I forget what it is called) and run for a longer while and check average speed.

[leech~~]

According to my GPS, the speed-o in everything I own is off by 2-5mph. SUV, Sled, Dual sport bike.

[JOHNBIGDOG]

I would trust the GPS more then the Gauge on the vehicle.

*Most all speedometers are slow to some degree, if you rode a motorcycle its even worse, to save the OEM's butt, and to prevent speeding.

You cant believe how easy it is to be on the bike, be going 65, look down a little later and 80.... wrist gets heavy sometimes.

Another fun note, my VW Jetta has the normal MPH gauge, but then has a digital read out. They are off about 2mph, the gauge being slow. According to my gps the digital read out is darn near spot on though.