speedo calibration

[one_and_only2004]

hi all,
just throwing a set of 19" rims on the ute. where abouts would i go to get the speedo calibrated so that it reads correctly?

[Doctor Bob]

go to a holden dealer or someone with a scantool that can program the instrument cluster with the correct PPK value.

[one_and_only2004]

why thankyou sir

[Lafanter]

use a gps while driving to tell u speed and then check the diff

[daves8]

you shoulnt need to change anything as the overall diameter of the low profile tyre will be pretty similar to what you have now.

[one_and_only2004]

there's a fair difference between the two i've noticed. better safe than suspended...

[holden hurc]

here are some suggestions
go to dealer and check ppk setting to tyre size and get programmed or go to
Tire Size Calculator - tire & wheel plus sizing which can be handy
or when changing diff ratio formula is
OLDPPK/OLDRATIO=A
A*NEWRATIO=NEWPPK
to be programmed with tech2 from holden dealer