r u wanting to stick with the 14 inch rims??
i would try to upgrade wheels/and tires while you're at it man.. you can pickup a set of 16's or 17's on craigslist all the time.. and all stock 6 bolt chevy wheels will fit once bored out.
2119 Kahstumz*Wii Wii*'s is correct. If you stay with a 14in rim than the best you can do is a 60 series tire.some tire shops are willing to run a smaller tire width and strech it so it will look like a smaller series tire.thats not good if you like to hang corners at high speeds.the side wall gives out and you go into the wall or pole.