I have the stock sport alloys. Other then the 205's having a slightly larger contact patch and slightly smaller diameter is there anything else I should know about? I am looking at the BF Goodrich Sport's and the guy at Costco advised me to get the 195/55. Any input? Which should I get? I only care a little about Eco and I dont track my car.

I apologize in advance if this has been covered

 

Your speedo will be off a bit check this site Wheel / tire size calculator / comparer - RIMS-N-TIRES

 

for stock wheels, just get the stock sized tires.

the wheel width is only 6" i think and it's too narrow to support a
wider tire to have much benefit.