Hey bud. Increase width not rolling diameter. That will give you more traction. Plus, if you increase the diameter of the wheel, you change your final drive ratio. Therefore your car will become slower, but have lower rpm at 100 and a higher top speed. Not necessarily good things in a car with zero torque from the factory. The guys above have the right idea. 14s and 15s are plentiful, you will find most 80s rwd jap cars have the correct stud pattern. Its 4 x 4.5 inches or as we say, 4 x 114.3 if you were wondering.
As far as what will fit, thats really determined by a number of factors such as offset of the rim, diameter of the wheel, rolling diameter and how much stretch the tyre has. Its a bit of trial and error. The offsets mentioned above will fit easy. Probably the biggest width you will make fit easy is an 8j, but 7j are plenty and will fit in a wider range of offsets. 6s are fine too, at the end of the day most people seem to stretch the tyre over them so they run the same size tyre on anywhere from an 9j to a 5.5j, just the looks change in that case, not so much traction as its still the same tyre. If the point is to get more traction its hard to get bigger than a 205 on the car in a decent offset.