Whatever you do, don't buy the Bridgestone M58!!
Earlier in the season, Dave and I put new tires on. I ordered a set of Michelin M12s. Dave had a new set of Bridgestone M58's lying around that he decided to put on,as his S12's had lasted a good long year. (I have a KTM200EXC, he has a KTM250MXC)
Well, here it is about 200 miles or so later. The knobs are still good on my M12 rear, although I haven't decided how much I like them yet. The M58 on his bike is junk. About every other knob is chunked, some of them severly. I should take a picture with the digital camera and post it for you. The knobs that aren't chunked off are rounded severly. We've both ridden the same terrain, and it is amazing the difference in tire wear.