I am a little confused about sizing of lug nuts. I need to get a set of lug nuts for my 15x8 Weld Prostars and they say they require a shank length 0f 1.31 to 1.38. Advance Auto has some chrome Dorman 711-302 that say they have a shank length of 1.31. If a lug has M12x1.5 stamped on it, does that mean the shank is 1.5"? I am just going by the pic on the website. It looks like it says 1.5 on that so does the 1.5 actually mean the shank length or will it be 1.31 when you put the washer on? Confused.