Trying to get my 79 ready to do some auto cross occasionally. I've got solid subframe bushings, subframe connectors, g-braces, moog 5610 springs in front and a 1 1/4 ft swaybar. Everything else is stock other than the drive train. I would like to keep the white letter tire look. I know it's not the best thing to keep the 15" tires, but I'm partial to the old school look. I currently have 235/60R15 in the front and 255/60R15 in the back. I'm wondering if it would be beneficial to go to something wider for only occasional track use or not. Will it make a drastic difference in times?