I was wanting to get a set of wheel just for racing road courses or autocross as for wheels I was looking on OZ, Enkei and BBS buy would anyone know the widest wheel I can get in the front and the widest in the back?

I was looking at 8.5 in the front and 9.5 in the back would that work or would it rub? Any recommendations?

As for the slicks my instructor at the track in sebring was running BF Goodrich g-Force™ R1, but I was also looking at the Nitto NT01 and NT555R2 and also the hoosier A6 or R6. Any recommendations for tires as well?

http://i294.photobucket.com/albums/mm102/zosoboogie/CHINSEBRINGApr18-192009DL-1094Mediu.jpg

Opps if I had different wheel sizes then i can't rotate them so would my best wheel size be 18 X 8.5???

I put 9" up front and 9.5 in rear, so you can run 9" all around. Also check out the NT05 from Nitto.

Looks like you have the wheel size questions answered, and of course lighter is better.
With regards to tires, All I can say is I've seen people do very well on AutoX with the Kumho V710s.

In general, I would NOT put wider wheels on the back, unless you're driving a Porsche. It would give you a lot of understeer. And all kinds of pains with not being able to switch the front and rear wheels for even wear.

For the tires the most important advice is: get new tires. You may have a good luck with picking tires from professional teams, if they've been run once and thrown away. But don't buy the "I've only had on event on them last year" tires. These are generally garbage, even if there is almost no wear on the tread. The rubber hardens and loses grip. Well, with one exception: last year's autocross compound (like Hoosier A6) that was worn and has hardened over time might work pretty decent on the track when it gets the extra temperature.

Other than that, depends on your usage. For autocross, your choice is pretty much between Kumho V710 and Hoosier A6. Kumho is a little cheaper and lasts longer. Hoosier is supposedly a little quicker. One caveat is: Kumho has recently been selling the tires manufactured in 2005 and stored for 4 years. These probably won't be as good as the recently manufactured ones. Ask your supplier the manufacture date before ordering. Kumho has two formats: "round-shoulder" and "square-shoulder". The square-shoulder format is new, and you'll get the recent tires guaranteed.

For the track: Hoosier R6, Nitto or Toyo, BFG R1, again Kumho V710. V710 would probably have to be shaved for the track use. The Grassroots Motorsports magazine ran a comparison last year. I think, V710, BFG R1 and Hoosier R6 were at the top. Toyo is generally considered longer-lasting, it would not be quite as fast but can last for a couple of years.