From a looks standpoint, I'm not sure about big wheels on an early car. I have the same decision to make in a month or two, since the "Euro T/A"s I have now have less traction than the 4/$99 special at Pep Boys. I considered getting a set of 16s, but I really like the look of the 15s, so I'm going to try and find good rubber for them.
The highest performance option is 205/50 front and 225/50 rear. Many stiff and sticky tires are available in these sizes, such as the BFG KD, Yoko A032R, Toyo RA-1 and the new Michelin Sport Cup. If you go down a step to the S-03, Toyo T1S, or Dunlop 9000, you can get 205/55s for the front, which will look better and match the 225/50 rears in diameter. Unfortunately my favorite street tire--the Yoko AVS Sport--doesn't come in 15".
One thing to consider is that tire sizes vary widely between manufacturers. For example:
My 245/50 Euro T/As - 10.2" wide = really 259mm
245/50 SP8000s - 9.6" wide = really 244mm
225/50 BFG KDs - 9.2" wide = really 234mm
225/50 S-03s - 9.3" wide = really 236mm
225/50 Yoko ES100 - 9.0" wide = really 229mm
So, depending on the brand you choose, a nominally 225 width tire can be only a few mm narrower than the "monster" 245s. Plus, you'll get 2-3% lower gearing, which I know I can sure use.
Here is how it looks now. The rears are like big bouncy balloons!
