Last Sport bike I commuted on would get 5k or a rear tire and 10k on the front tire, front brakes and chain and sprockets...Granted I rode pretty hard but still.
I know what you mean about the off brand crap. I had a buddy that used to always ride on Cheng Shin, don't know if I spelled it right. Or if they are still around. But I can say that they were damn near like riding on the snow. Sure they were close to half of Dunlop/Metzeler/Bridgestone but it made riding down right scary.
Can't help but wonder if any bike tire is capable of 20K?
