I grabbed some brand new Scion TC wheels/tires for only $600 off a kid who just bouhgt a new Scion. They fit perfectly on the Prius, but if you do the math they're about 2.5% larger in circumference. Is there a way to recall the odometer so the MPG figure doesn't lower by ~2.5% due to odo error? I've noticed MPG figures drop to the low 40's (from high 40's), but some of this is due to odo error and winter weather. BTW, the new pic was taken today at the Hoover dam (also got the windows tinted)
There's a tire reset button in one of the MFD menus, I don't recall the path, that tells the unit to start measuring again. You're supposed to reset it after rotating or getting new tires. That may help some. Look for some of the tire discussions which have comparisons of different sized tires and their effect on true MPG. Sorry I can't recall more.
The reset button is located on the "User" sub-level of the menu page. Calibration is on page 1 of 4, select "Adjust," then go select the tire change option.
I believe this affects the NAV accuracy only and not the spedo/odo itself. The former compares rotational wheel speed w/ GPS measured speed. This data is useful for when GPS isn't available so that the NAV system can guess your location from the combination of gyroscope and speed sensor input.
