I do belive that the stock tires size is a 225/60/16. If you went to a 205 you would be putting a pizza cutter thin tire, also it wouldn't be as tall because of the ratio. Hope that will help out some.
If you are looking for a decent tire for the stock rim, might I recommend the 235/55/16 size I ran on the stock front rims for about 15,000-20,000kms. Very nice size with the right brand.