So apparently 20s on a forte is a bad idea. Looking at some posts over at forteforum, someone had 20s and they were rubbing up on the wheel wells at times. Apparently you will also feel potholes and bumps greater than if you were to keep the stock tires. No one has many good things to say about the 20s unfortunately.
not sure of the look you are going for, but besides being not good functionally, the look of a 20 on these cars just doesn't work very well.
Since looks are subjective (to each their own), i'll give you my experience with a 19" rim on my sedan, before i sold them.
- I have coilovers and they are dropped pretty low and dampening set very stiff. On some aggressive bumps or speed bumps in the roads, the tires would contact the wheel wells.
- road noise was considerably larger, this mostly coming from the low-profile tire. I believe my tire size was 235/35/19
- aside from the road noise, the ride is considerably worse. It got even worse as the tires wore.
- putting a 20" setup on stock suspension is going to look VERY out of place (read: dumb). If you get them on there and lower the car, then you will get the rubbing problems as i mentioned previously.
If I were you, I would stick with 18", get a good offset that isn't stock, but not "hellaflush" either, and a nice lowering spring or coilover and the car will look damn good.
It will also keep the road noise to a minimum and you'll stay fairly close to stock as far as ride comfort goes. Jsut make sure you get the right aspect ratio and don't get a tire that's too low profile.