I have a 20007 XC90 2.3 AWD. I am trying to order rotors and everyone I have talked to says I need to measure them to see what size I need. I eyeballed a tape measure across and read it to be roughly 339mm. Judging by the fact that the only options I see for my set up and age is 316mm or 336mm, am I correct to assume I need the 336mm size?<p>Thanks!!