My new Metzeler Tourance tires have two red painted dots on them. I have heard that this is supposed to be the 'heavy' spot/side of the tire itself and should be mounted OPPOSITE of the valve stem. I have also heard that the painted dot should be mounted WITH the valve stem. Which is correct? What is the TRUE purpose of the painted dot? I'd like to get to the bottom of this with some concrete proof and not just some people's guesses! Ok, this will be my last question on this whole tire changing gig...I swear!