Bridestone B12 tires come in two flavours, regular and SS. *The regular are aimed for fast road with the occasional trackday and can handle wet roads slightly better than the BT012SS. *The SS version is aimed at trackdays, very fast road riding and are okay in the wet. *The BT012 has a mono-sprial belt, just like the BT010, whereas the BT012SS has a dual-spiral belt - what's a spira belt? *I dunno but you can find out if you speak to a Bridgestone techy, I think it's to do with the tyre carcass and how it's weaved together.
At least that is what a Bridgestone tech told me on the phone. *Somehow on the BT012SS the belts work together to make the tyre stiffer or stronger when in a corner getting the power on so that the tyre holds it shape and contact patch better. *It's only noticeable under extremes such as track riding or very fast road riding.
If you get 4,000 miles on BT012 then expect about 3,000 miles out of BT012SS, so the tech told me.
BT-012SS - Bridgestone website info
BT-012 - Bridgestone website info
MCN did a review of supersports tyres at *MCN Supersports Tyre Review 2001
MCN Product Reviews List
I've just changed from BT012 regular to BT012SS and before I changed I was messing about accelerating to about jogging speed and then jamming on the front brake. *The front would dive, bottom out the suspension (I think) and then the front tyre would skid about 9 inches. *I did this on my driveway which is made of concrete, it was in the dry and it's not dusty.
After changing from worn BT012 to new BT012SS with 50 miles on them I tried the same test again. *This time the front tyre stuck to the concrete and the back of the bike went about 3 inches into the air! *I tried it again and again, each time the front would NOT skid, it just kept making the back wheel lift.
Conclusion - new BT012ss are stickier than 4,000 mile old BT012 regular!
PS - I did two trackdays in the novice group on the BT012 and they were great. *I thought it was a good tyre and I was happy with it but the BT012SS seem to be just that little bit better, it's only fractional but it's just about noticeable. *Of course this could just be going from old tyres to new tyres.
Hope this helps.