Speedo reading 2 mph higher than GPS

[Mudduck]

Mine was 2mph off. I used FORScan and then my COBB to adjust. Now My Speedo/GPS/Wolf-box dash cam all match. When passing by the speed indicators, or construction signs they'll flash 69-70(for example) back and forth. seems like I'm .5 MPH off. I can live with that. It will change as the tires wear I'm sure.

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[rlhdweman]

Wondering if others found this. Tires are Firestone all season 225/65R17

This can happen with different brands of tires or even the same brand but a different model of tire, I replaced my continentals with another line of continentals & had the same experience, both were the same 225/65r17 & the speedo read 2 mph fast even though the replacement tires had an extra 1/4 of tread when new.

 

[Connect]

my speedo is regularly 2mph more than gps, sometimes even 3.

 

[Chops]

Back in the mech days, an incorrect speedometer meant an incorrect odometer too?

Now that both are computed - that is no longer an issue.? (Speedometer can be overstated independent of the odometer).

“Turning back an odometer” will require different techniques

 

[TheSEARCH]

When new my 2023 Hybrid xlt speedo matched gps maybe .5 mph off. But super close. So have my last four cars. To say that is normal I would disagree. BUT my snow tires Blizzaks were off by 2 mph which I hated. Now I replaced my OEM tire with Tour 54 tire. Off the exact same amount my snow were. I got the usb to obd plug and forscan and reset it so it was perfect. I find it unacceptable to be off by 2 mph. Mine would say 60 but really 58 mph. I say it is NOT normal to be off by 2 or more Maybe one at MOST.

 

[kevink]

Wondering if others found this. Tires are Firestone all season 225/65R17

Mine is probably 1/2 mph off at 70+. My car is about 3 mph off.
The 2 Ford pickups were essentially right on. My 95 Ford Taurus was way off the other way, I never looked into why. My BMW was about the same 3mph off you see.

 

[playinboats]

The thing I noticed was that when I compiled the fuel consumption with real data, that was off about 2 gpm So the miles driven was higher and time frame off. (Note) just completed a 2600 mile round trip

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