You do not need them unless you are on the track. They are only good for a few heat cycles and the wear life is short. Most people who hit the twisties are partial to the 180 tire. If you live in Fla with no curves get either.
I'm getting tired of people saying the Power Race tires are only good for the track.. I know from first hand experience that everything I've heard about them not being good on the street is a bunch of crap!! I've been running the Power medium/soft dual compound race tires on the street now for a few months and I absolutely love them. They seem to be wearing evenly, they are definately getting hot because the rubber is blistering, and after 500 miles they still feel great.. In fact, I think they feel better now than they did for the first few rides. Even at outside temps below 60 degrees they still warm up nicely. I was very hesitant to buy them because of things I was hearing but I figured I'd try them for myself and see for sure. Now I know.. Softer and stickier is better no matter where you ride. Now I will say, they totally suck in the rain, but I don't ride in the rain anyway... Also, I always warm them up before I start to hammer. These things stick so good, I doubt I will ever go back. My last tire prior to these was the Pilot Power. They were good but not nearly as good as the Race.. :fact As for miles, if I get 1,500 miles out of them I'll be happy. If you ride hard your only gonna get 3,000 miles out of a good street tire anyway. I'd much rather spend the $300 every 1,500 miles and know I'm on the stickiest shit I can buy for the street. Just my .2
Oh yeah.. I'm running the 190. I tried the 180 before and it made the bike feel more unstable. The bike did turn in a liitle better but I got the same result from raising the forks in the tree. Again, just my .2