I get the feeling that they offer no extra performance over 18s. Maybe decreased performance. My reasoning is that all the exotic cars that have 3 times the power come with stock 18s with larger sidewalls. I mean, an F360 or a 6.0 VT can surely take 19s but they never put them on. Even the F360 challenge has 18 inch CH wheels. I don't think Lamborghini, Ferrari or Porsche offers any stock sports car with any wheel over 18 inches.