Gary, in most cases the z rated tires are made to be stickier in their tread compounds, but there is no rule that makes this true. It is usually diffrent for every tire. Howver, I know pleanty of v rated tires that are stickier than the z rated competitors, and vice versa.....it all depends on the specific comparison. As for you tirerack??? response question, moderating this board is something that I do as a service that I do not get paid for. I do it to be helpful to fellow BMW owners like myself. I always try to answer posts as fast as possible, but if I am out of town, a Sunday afternoon post will not be answered till Monday. All posts will be responded to as fast as possible, and reposting a ???where are you message on the same Sunday afternoon that the message was posted only makes one want to answer other posts first.