I am not saying the 13's are the best option for every 4 cylinder car. I am saying that you want to get as much tire under the car as rules will allow and still fit over the brakes. At min I would suggest going with the 225 size in either 14 or 15. I would also not just look at the kuhmo tires but get a wheel that will hold a hoosier so if you decide to get real serious you don't need new wheels. The 225/45/15 might be a good comprimize for you. Not sure. Go to the specs on the tire rack site and you can look at what size wheel you need to fit that tire. You want the wider wheel. Don't choose the 6.5 inch wheel if that is on the low end of the range that the manufacture recommend. Look for the high end. That means a 7 inch wheel at min to run the 225 size tire.