[WolfSongX]

The Road and Track test showed that two different diameter wheels of a similar mass running the same compound and design of performance tire, the 17" tire was several 10ths quicker than the 18". All other factors being equal, this means that the difference in the rotational mass is significant at the stock power levels. This was also backed up by the test drivers noting that the car was more sluggish at certain points.

With the basic bolt-ons and a tune, these cars don't tend to make a lot of extra power unless you go FI, so by going to 18" rims and increasing your rotational mass, you are in fact giving up the power you did gain with your other mods.

Personally, my first choice would be some super lightweight forged 17x8's or 17x7.5's so I can run a 225 series tire and have a slightly bigger contact patch than the 215's, but mainly to take advantage of the slightly cheaper rubber options when I have to replace the tires, especially since forged rims are so freaking expensive.

However since I rarely get to the track or autocross these days, then I can consider this to be just a street application only. That way I can drop the ultra-light and expensive forged wheels from my criteria since the extra couple of pounds per wheel isn't going to matter as much. Instead I can look at just doing cool-looking inexpensive 17's that are lighter than the stock wheels and will cost a fraction of what the forged wheels cost. As long as they're a few pounds lighter than the stock wheels, there will not be a performance decrease, even with heavier/wider tires and I can take advantage of stickier rubber on a slightly wider rim.