Another tire recalibration thread...

[jwmaier1215]

You guessed it, it's another "help me recalibrate my truck."

I did find this in another thread:

Originally Posted by Longshot270

The easiest way I have found to get the tire size accurate with a GPS is to set your tire size to something you know is wrong, like 2400, clear the odometer on your truck and on the GPS, drive 10 miles then input the numbers as shown.

(GPS Miles/Truck miles) X 2400 = New Tire Size

So I did this. However, I wanted to make sure of something.

Here is what I got:

11.5 miles on the GPS = 10.4 miles in the truck odometer.
65 mph on the GPS = 59 MPH on the truck speedometer.

But here's my question: I could use the formula above, but instead of 2400, I want to input whatever my setting was originally, right? So for me, I had 2569 inputed (JackandJanet tried helping on F-150online back when I first got the gryphon and I thought this was correct and never checked it with the GPS until now). Anyway, so what I want to equate is:

11.5/10.4 X 2569....which would equal a new size of 2841. But isn't that taller than a stock 35in tire? JackandJanet said the edge manual says a stock 35in tire is 2792. So how can it be taller?

Here is the thread I'm referring to:
Edge Evolution Programer - F150online Forums

Is there a simple formual I can use?

/Yeah I know I sound like a total airhead in that link (i'm 95'f-150). I was unfamiliar with the whole ordeal.

I guess I should give a detailed description of the truck:
2001 F-150 4x4 Off-Road package
5.4 triton xlt
Gryphon programmer (with custom tunes)
K&N CAI
35x12.5x17 BF Goodrich MT's
Flowmaster si/do super 40 exhaust
3.73 gear ratio (I think, I can't find on my vin sticker where it says what gear ratio I do in fact have. And this could be the problem as well.)

I don't think all that is necessary, but rather be safe than sorry.

Thanks for any help guys! Oh and btw, it's a wonder I haven't gotten a speeding ticket yet! I usually run 65-67 in a 60mph zone (so actual 70-72ish mph).