I have started autocrossing my s2k in BStock. I want to get either Kumo's or Hoosiers and will run them on separate wheels for track only. What tire size and wheels are recommended to remain in the stock class? It does not appear that either Kumo or Hoosiers are made in the 205/55 - 16 stock size for the front end...

 

You can get a 205/225 mixture in the new Kumho Ecsta V700s but they're narrower than the 225/245 sizes that most folks run (Hossier folks do, too). Without a large front swaybar, however, you may want to consider the 265 rears. They're too tall, causing a small decrease in acceleration, but the extra width helps keep the rearend in line. That'd be a lot cheaper than ALSO buying a sway bar, especially if you're just learning the ropes. Fast tires won't give you as much as experience...

 

I seen some one from the Detroit region running Hoosier A3S03 215/40's front and 245/45's rear on the stock front sway bar.
The fast set up the top drivers use is 225/50 front 245/45 rear on A3S03 but this set up definitely requires a competition front sway bar.