speedometer correction

[250]

speedometer correction
Hi All,

I wsa going to increase my tire size from 145/R75/16 (stock)
to 265/R75/16 and was told that all I needed to do was to change the VSS gear. My local Ford store is of no help.. They say they have no gear listing for a 265 16 tire. Can anyone give me specific information about this. Part#s, pnone #s, or web sites??

1998, 4x4 250 light duty, 4.6

Regards,
David

[lanero]

Do a search here for "Speedo Calibration". I know it has come up in these forums a few times.
As far as the gear goes, you don't have one. That is why the parts people couldn't find one. The calibration is done with the speedometer and a certain procedure. I don't know the procedure, but I do know that it has been posted on these forums before.

Roger Lane
Test Analyst
Sr. Automated Test Engineer

[beratte]

Is the 98 F-250 the old style or the new style truck?

[mtraum]

I am going to assume that you intended to say 245 not 145. 145 would be a very small truck tire!

If you changed from a 245/75/16 tire to a 265/75/16 tire your final drive would only change about 3%. If your speedo registered 60 you would actually only be going 62. I would hardly worry about that small of a change in gearing in terms of redoing your speedo.

[85351ho]

to recalibrate the speedo, the dealer should have a computer that they hook up to the truck's computer, its all computerized now, no more speedo gears,

1985 F-150/351Ho/c6/4wd~96,000 miles
1979 F-150extcab4x4/460/c6/6inchlift w/60rear44frnt 4.10 gears, 250 springs
37 boggers

[Chuck P.]