It does wonders on street tires too. Even at the dragstrip. The tires on my 95 when I bought it were pure dogshit. But they were new, so I couldn't justify ditching them. Siping them increased their grip in wet and dry weather remarkably.

The tires on the other Bonneville have been siped for 3 years (2 different sets).

They make wonderful tires in my exprience. I had a set of 'Stones on the 77 they lasted along time!