If you're on OEM tires, absolutely go to better tires before different wheels. A wider wheel on the oem tires will make no appreciable difference but will instantly bump you to STX.
I would recommend better tires. Best choices for a high performance summer tire would be the BFG Rival, Hankook RS3, or Dunlop ZII. After that, your next three mods should be:
1. Seat Time
2. Seat Time
3. Even More Seat Time
Experience will make you quick
