Tire Size

[BigSur]

Originally Posted by JackandJanet

4 miles in 140 miles is a 2.9% error. Multiply your current TS by 0.971 to correct to the GPS reading.

You shouldn't be in any danger playing with the part throttle shifting yourself. I think I'd REDUCE the 1-2 upshift and downshift by the max (-2) and then maybe add to the Torque Converter unlock/lock speeds by the max for both 1st and 2nd gear. (I'm trying to keep the TC from locking right away so I think values of +2 in 1st and +3 in 2nd might work. Anyway, it's worth a try.

- Jack

Thanks I might just do that. I'll let you know how it works out.

[agood1]

Hey Guys,
I had to buy a new set of tires so I have to reset my TS in the Gryphon. I went back to the stock tire size of 275/65/18.
Right now with the Gryphon set at 2560, My GPS is showing 2-3 MPH slower than the Speedo. The Gryphon is showing in between the GPS and the Speedo.
Should I increase the MM size and how much?

[Jackpine]

Originally Posted by agood1

Hey Guys,
I had to buy a new set of tires so I have to reset my TS in the Gryphon. I went back to the stock tire size of 275/65/18.
Right now with the Gryphon set at 2560, My GPS is showing 2-3 MPH slower than the Speedo. The Gryphon is showing in between the GPS and the Speedo.
Should I increase the MM size and how much?

Actually, I'd say you are almost dead on if you see no more than about 1-1.5 mph difference between your GPS and the Gryphon. But, to get them to agree, you need to decrease your TS, not increase it. Assuming the difference you see is at 70 mph, you have a 1.4-2% error. Try reducing your TS to 2524mm.

And remember, the dash speedo is always going to read a bit faster than you're traveling, because Ford builds them that way.

- Jack