I had a free set & tested them @ road atlanta a couple months ago & posted the results here.search for the post for more specifics. They were for my porsche & I will check my trailer for the treadwear tonite & post.
My observations & since they were released to Porsche Sizes first, the PCA club racers has a (relitively) a lot of miles on em.
1) Drivers ed guys swear buy them, the racers swear at them.
2) Unshaven, forget it
3) they like low low pressures
4) They run small, IE) a 245 Cup = 225 hoosier tread width
5) Unshaven they last forever, so they make a good novice tire
6) I tested unshaven & although after experimenting with hot pressures, we did get the lap times down to Khumo levels but it was a scary ride. It took me all day to get the confidence to go flat in a few places that , normally on street pilots, I wouldnt think twice. The low tire pressures made for sidewall flex & a weird sensation on turn in, once hot the would stick.
7)tested on a 2700 lb car with 200 HP, Maybee the vipers weight & hp will allow a higer starting pressure & less sidewall flex
8)I stuck with the hoosiers & are using the cup for interm. rain tires.
9) The guys I know who like them say it takes 5 laps or so to come in
10) none of the fast guys in our last 3 club races used them,(VIR, Carolina, Roebling) the winners all had hoosiers.