Accuracy speed readout

[GNONYX]

I have a digital dash ( Casper upgraded chip) display and while test driving I notice speed reading is about 12 miles faster then the GPS reading. Is it possible the VSS Buffer Module needs to be replace?
Thanks

 

[aminga]

What does the scanmaster say

 

[GNONYX]

What does the scanmaster say

Scanmaster reads the same as the dash display.

 

[aminga]

What sized tires?

 

[GNONYX]

What sized tires?

Right now 15" stock rims, Do you think if I replace with 16" I would see the display reading correct speed displacement?

 

[groumoutis]

What size tires not the rims. Are they low profile? Overall height which throws off the number of revolutions over a given distance because of the circumference.

 

[GNONYX]

What size tires not the rims. Are they low profile? Overall height which throws off the number of revolutions over a given distance because of the circumference.

My correction, stock rims with 215/65-15 tires, In the future will replace with (rear) 255/50-16 tires (front) 245/50-16

 

[aminga]

Stock 3:42 rear gear?

 

[GNONYX]

Stock 3:42 rear gear?

Yes Stock 3:42 rear gear

 

[aminga]

Change the speedo gear in the transmission

 

[GNONYX]

Change the speedo gear in the transmission

I believe there are several types of speedo gear for tranny. How do you know besides the color which is the correct one ?

 

[GNONYX]

As to the 1st thread, Is it possible the VSS Buffer Module needs to be replace?