I just went through a lot of this for my soon to be track car. Hopefully i can add a little information to help your decision. Personally I completely agree with the 17" rim decision
but from what I've read the difference in handling perform is not noticeably different when increasing to an 18" rim. The biggest difference is that they weight more and most of the tires you would purchase for them increase to overall diameter which will reduce your acceleration, unless you buy the very small aspect ratio tires.
You may want to check out this thread if you haven't already. There is an enormous amount of information here!
http://www.ft86club.com/forums/showt...=wheel+fitment
Just doing a little searching, if you are buying on a budget and don't want to go overboard i would suggest going with 7.5" to 8". You will have a decent selection of brands and style to choose from.
Based on the tire sizes you posted 8" will be the most practical to use and you can choose any of the 3 tire sizes that you mentioned.
I haven't looked on the twins but make sure that the wheel and tire combo you choose will fit in the car without rubbing.
There are a lot of things to consider with respect to handling and car performance. For example, going with the wider wheel and tire will improve handling to a point but with wider tire comes more weight that you are adding to the car.
Some of the biggest handling improvements are simply made by the choice of tire compound and side wall stiffness.
Happy hunting my friend!