Tire size calibration

[wireman_67]

I just bought a '95 Chevy K2500 3.73 truck and my brother has a '97 k2500 4.10 truck. We both run 285's and neither of our speedometers have beec recalibrated. How do we do this? Is this something we can do or does the dealer have to do it?

[redbird2]

Get the 6.5 book Jim printed vol 1 it tells you how to adjust your speedo calibration. a little math and little time you will be all set. if you have the dealer do one truck it will run appox 100-150 the book will cost you 25 so charge your brother and you all set (ha ha) lots of other great information in the book to use also.
Good Luck