looking for new rims for my qx60 couple of questions

Im trying to decide on 20" vs 22"...i want to keep my car looking somewhat professional b/c i use it for work. i think i can get away w 22" baseed on the pics i see but i was wonting if i can get a leger sidewall b/c i dont want a low profile for potholes and ride compromise reasons and i would also like to fill up the gap between the frame and tire. Ive heard that there is a sensor that determines the MPH ur car reads ive also heard that a larger circumference will throw that MPH off no matter what as there is no sensor? Anyone have any imput on this?