Does anyone have any experience with these tires? http://www.motorcycle-superstore.com/1/28/394/6209/ITEM/Shinko-Road-Race-Slick-Rear-Tire.aspx
Honestly, there are a lot of pretty good tires out there for the Ninja 250. Both Michelin and Pirelli make a full blown race tire for that bike. Bridgestone makes a track day tire, and I believe Dunlop has at least a track day possibly a race tire for the bike. I would stick to a reputable tire company and run a DOT race or trackday tire. If it starts spitting rain you'll be in a better position than on a slick and at least with Michelin, Pirelli and Bridgestone, there is a tire guy at the track to help you with setup/pressures etc. Just my $0.02, you're results may vary.
Customer Reviews for Shinko Road Race Slick Rear Tire: Love that SLICK!!! It's the only tire I use on the street and track, great tire. No burn out on a good day of racing. ....so I wouldn't give this much merrit when road race slicks aren't street legal!
Most aftermarket exhausts aren't street legal, but guys use them on the street. The tire probably sucks imho, but that review may be true to the best of that consumers knowledge.
Western Powersports handled Bridgestone last year but I don't know if they are still bringing in the race tires.