Having changed tires from 245X75 to 285X75 I am guessing that the trip functions and the fuel info averages on the overhead computer are no longer accurate. I recieved some advise on products to correct the speedo and now I am wondering if the trip computer can be reprogramed for the new tire size? Seems to me that it probably works using RPM vs fuel flow as compared to tire size but dunno just guessing anyone ever look into this one

 

It gets it's info from the same place as the speedo.
Correct the speedo and you've corrected the overhead.
(well, back to however accurate it was in the first place)

Once you add injectors or fueling box into the mix, it will never be accurate again,
as far as Distance to Empty, average MPG and current MPG.

Pretty sure it just uses fuel flow vs vehicle speed and distance traveled to figure mpg.

phox