Seen these on various US websites, street legal tyres desgined to compete against Renns/SCs/D208GPAs etc, I've always preferred bridgestones, and they come in the holy grail of tyre sizes 

, a 190/55. 
 Anyone used them, and where can I get a pair at a good price? 
 Curious cos I have never seen them on trackday/race bikes, was wondering if there's a good reason for that! 
