So I've read a couple of people say that to get a rough measurement of your clear coat thickness you can use a PTG and measure the paint on your door jambs, then measure one of the body panels and then subtract the difference and that will give a rough measurement of the total clear. I realize that this is only supposed to be a rough indicator, but I would think that this would only be somewhat valid if the basecoat thickness is uniform everywhere. I guess what I'm wondering is if the clear is thinner in the door jambs then why wouldn't the basecoat be thinner as well. My thinking is that this method of measurement is only fairly accurate if the thickness of the basecoat in the door jambs is the same (or close to it) on the body panels.