l am replacing my 16'' wheels with 18'' wheels.l do not want my speedometer and odometer to be incorrect.

Any tips or pointers on how to adjust the gear ratio without paying a ridiculous price at a dealer?The old tires are 29.1'' outside diameter and the new ones 29.7''.721 revs/mile vs. 701.

If it can be done, the dealer or someone with the right scan tool will have to do it>

computer has to be reset for the tires, probably have to go to dealer for re-calibration

If it can be done, the dealer will have to do it..or at least someone who can recalibrate the PCM. Ford dealer tools usually wo not allow much leeway in the recal anyway (it used to allow for almost any size.. l had one recently the guy went up one size & l could not do it for him)

the 4x4 community does make a kit to fool the PCM & it is hardwired into the wires going from the ABS module to the PCM.. but this is last ditch effort.. power programmers sometimes allow u to adjust but l do not know of any made for the Mariner

Just from personal experience as a Linc/Merc Technician. Everyone that puts bigger wheels & tires on these experiences Vibration problems.