How much you want to spend? The wheels are one thing. The tires that go on them keep getting more expensive the larger the rim size. I prefer 17" but I've seen 18"s that look and function really good. I keep away from "Z rated" tires. They tend to burn up and the need to be replaced sooner than "W rated" I go with "M+S" for every day driving, but keep another set in the garage for play. Mickey Thompson makes a good pair of slicks for a 17" wheel. Also, the larger the rim size the more your suspension will have to work harder and you will feel a more rough ride. So it's a trade off with looking cool rollin on 20"s versus a comfortable car that can run on 17"s or 18"s that people like to ride in with you. Hope this helped a little.
A forum community dedicated to Ford Mustang owners and enthusiasts. Come join the discussion about performance, builds, modifications, reviews, engine swaps, classifieds, troubleshooting, maintenance, and more!