Each wheel and tyre size/brand had its own characteristics. You could consider 8.5ins x 18 (f) and ®10x18 with 235/40 or 245/40 on the front and 265/35 or 275/35 Bridgestone SO3 on the rear. IMO this gives nice progressive handling, even on wet roads the breakaway is relatively slow giving you time to apply the correct amount of opposite lock. 18" if you pick something with class like a Supra deserves, look super. Some of the best IMO are AZEV, blitz or Antera. Azev are very strong and do most of their wheels to fit Supra's, Blitz are excellent but VERY expensive, and Antera are the lowest cost of the 3 but very well finished and pretty strong too.
Here is a very nice set (dont know who makes them, but they look well)
http://lisupras.com/SupraMembers/SeanA/1.jpg
If I was buying again I'd probably go for AZEV. I'd never buy a set that I had not seen a pic of the wheels on a Supra. Too much cost to take chances! :-)