Which tire size?

[Sburn]

Originally Posted by kevins669

Hi all,

I have been trying to get my speedo and the gryphon to match.

I upgraded the tires in the 04 to 275/65R18...

The gryphon and my gps are pretty much on target, but the speedo is always 2 MPH higher...

No matter what custom tire size I enter.

Any thougts???

Thanks,

Kevin

That's by design. Ford programs in a +3% bias in the speedo reading. If your Gryphon matches your GPS, it sounds like you're OK.

[JWBFX4]

Originally Posted by Sburn

That's by design. Ford programs in a +3% bias in the speedo reading. If your Gryphon matches your GPS, it sounds like you're OK.

x2 exactly right, it seems as if ford wanted to cut down on a few speeding tickets by having it programmed 2 mph fast.