is it possible with the use of an obdII interface cable and software to reflash my ecu to account for a rim/tire size change?
example - i went from a 225/35/19 to a 225/35/18 and i want my mileage and mph to be correct.
is this something only the dealership can do, or can this be done at home with proper software?

 

i might be wrong but i dont think all that would be necessary. the ecu should adjust automatically.

 

not trying to be a pill, but how would the ecu know that a differnt size rim was installed? all the ecu knows is rotations of the tire. with a smaller rim, the wheel rotates faster, and the ecu translates that into higher mph.. unless you know something i don't?
I know the 05 up TC has the TPMWS, but the 1st gen xa/xb's don't. I do believe that the 2ng gen xb also has the tire pressure monitoring warning system, which will sence tire size based on rotation and resonant vibrations.
advise please.