You have a selection of summer tires in ultra high performance, max performance, and extreme performance which pretty much explains itself. Of those the Dunlop Direzza Sport Z1 Star Spec is the most sticky and a lot of people love them for Auto cross but also have the lower tread wear rating. I am pretty sure these are better than the rt615's in both performance&practicality although slightly more expensive. I currently run the Sumitomo HTR Z III & really happy so far. They are not noisy, have a nice ride, and are enjoyable in the twisties. Price can not be beat! My general plan is to beat the crap out of them since they are so cheap anyway. So, for your wants, this one is my recommendation. Just always remember the operating temps for all of these tires are 60deg+. When the time comes again I'm going for a set of tires in the extreme performance category as I would like to reach higher levels of performance at the track/auto-x.
