I think there is the htr z and the htrzII's I'm running the htrz's and am very happy. For a street tire they do a great job, dry street traction is good, wet traction is acceptable and from everyone I've talked to mileage is great plus the price is hard to beat.
Now the htrzII's I hear their dry traction is better, but their wet traction is worse, also heard they don't get as many miles. Just hear say though.