possible to have RPO mistake on 2004 denali?

[BirchyBoy]

So I checked mine today. Using the Torque app and gps here are the results.

2,000 RPM
Speedometer: 65 MPH
Torque app: 66 MPH
GPS app: 70 MPH

So my speedometer is off 1 mph from what the OBD port shows. Gps shows 70 because the larger wheels and tires.

I was surprised that there is a 4 mph difference with just a slightly larger tire.

Wouldn't the GPS app be calculating the speed based on satellite changes, and not be affected by the tires and wheels?

 

[YukonXL04]

Wouldn't the GPS app be calculating the speed based on satellite changes, and not be affected by the tires and wheels?

That is correct. My truck is actually going 70 mph. Which the GPS shows. The reason there is a difference between my speedometer and gps speed is because larger tires.

 

[redemn93]

put the scanner on the truck yesterday evening.

scanner - 2000 rpm
gauge - 2100
speedo - 66-67
gps - 68

i guess thats close enough. wonder if the AWD has anything to do with it.