Which tire size?

[Jackpine]

Originally Posted by Afrancis

Was just curious as to which tire size comes preloaded on the Gryphon? I got an 05 FX4 that comes stock with the 18", if I figured it up correctly my number should be 2559 (please correct me if Im wrong). The number that was preloaded was 2356, is that the 17"? Im mainly asking cause I want to be sure before I go making any changes. Thanks for any help with this. Also on a side note was just wondering if you guys got my HEX code I emailed to you a few days ago? Not trying to rush you, just dont want to have had my email lost in cyberspace, and end up finding out months down the road you never got it.

Afrancis, this value "2356" is a bogus value that seems to be a "placeholder" in PCM memory anytime you choose the custom options and DON'T "Reload Previous Settings" as a first step. The number "2559" sounds to me like the unloaded circumference of your tires (which is the same as mine). I've found a value of 2481 makes my speedometer and odometer accurate, so I'd recommend the same value to you. (It's close to a 7% rubber squish using Bill's calculator in Pegasus).

At the risk of boring everyone, I'm going to try to explain this Custom Options thing again.

IF you select a tune level and BYPASS the custom options choice, the Gear Ratio (GR) and the Tire Size (TS) will be taken from the VID section in the PCM's memory, which are factory values and they should have been correct for the vehicle when it was delivered. If you bypass custom options, everything will be set by your tune, and if you haven't installed new gears or bigger/smaller tires, you're good to go.

But - if you want to mess with ANY single one of the custom options or if you just want to see what's there, you'll have to choose the "Custom Options" selection. The moment you do, BOGUS values get loaded for TS and possibly GR!

IF you have done the "Custom Options" thing before, and IF you loaded correct values for GR and TS, you can "Load Previous Settings" as your next step to restore these correct values, as well as any other settings you had or changed when you last programmed the PCM to an advanced level. You can then review or change any of them and finally select "Done" to complete programming. These values become your new "Previous Settings".

If you have NEVER used the custom options menu before, I don't even think you have a "Load Previous Settings" choice (but I may be wrong). And, if you're IN the Custom Options menu, you will almost certainly have to correct the TS value and you MAY have to correct GR. Once you save them by selecting "Done", they become part of your "Previous Settings".

There! Hope I haven't confused things more.

- Jack

[Afrancis]

Thanks Jack, Ill just set mine to 2481 as you suggested. Didnt know the 2356 was a fake number, thought it might of been a preloaded TS by Bill.

[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

[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.