I have the new 315's on my rig, now I'm running 80-81 while indicating about 75mph. Want to get the speedo recalibrated...other than the "stealer" who else might have the ability to do so...a custom truck accessories store? How complicate is it...or a better question, how long does it take?

I dropped by the "stealer" today after work and was told it takes anywhere from 1-1.5 hours to perform...to which I replied "really?, really that long", to which donut Bob behind the counter replied "...yeah, you know, we have to access the computer then locate the speedometer settings...take a bunch of measurements...takes awhile with most...".

So, short of purchasing an after market unit to install on the transmission, what should a guy expect or look for when seeking to recalibrate?

 

Print this off and take it to the dealer.

Special service message 11789 & 11790 from 7/29/99

1. Ensure all harness connections are plugged in.
2. Using NGS and version 3.2 or higher service card, plug into the DCL connector.
3. Turn key on w/Engine off.
4. Select service bay functions.
5. Select ABS module or 4WABS module depending on application.
6. Select tire size/axle ratio configure.
7. Select tire size. If tire size is not listed use formula of: 63360 divided by the circumfrence of the tire measured in inches. Add 2 zeros in front of the solution. Enter this number into the NGS as the REV.Per MILE figure.
8. Select tone ring size and verify that 120 is programmed in.
9. Select <option> and press TRIGGER.
10. Select <vehicle> and press TRIGGER.
11. Press <DONE> and the module is reprogrammed.
12. Verify speedo accuracy.

Circumfrence is 2pi x radius. If I remember right a 35" (315x75R-16) tire is entered as 00602 revs per mile in step 7.

Takes about 30 minutes including the test drive.

 

Thanx Cookie. Now if I can just find a dealer to "cooperate" I should be good to go.


thanx