recalibrating speedometer on a new GT

[Greco]

Originally Posted by Jeff Chambers

Depends on the overall height of the tire. Are the 20" a bigger overall diameter? There is a certain amount of N/V that the computer will learn. Your other option if the dealer won't do it is to get a handheld tuner like the SCT Xcal2 and adjust it via the tune.

I'm a newbie on this stuff, but they're replacing the 17" factory wheels. I don't know what the overall diameter of the new wheels will be, but I was assuming they're bigger. They're 20x8.5 rims and I don't know the details of the tire they're putting on there. I need to find out. What does "N/V" mean? Is the handheld cabibrator easy to use? Where exactly does it plug in? Thanks, in advance.